diff --git a/30 days of code Solutions/Day-0.cpp b/30 days of code Solutions/Day-0.cpp
new file mode 100644
index 0000000..fbf069b
--- /dev/null
+++ b/30 days of code Solutions/Day-0.cpp	
@@ -0,0 +1,25 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+
+using namespace std;
+
+//--------------------------------------------------------------------
+
+
+int main() 
+{
+    
+    string input_string; 
+    
+    getline(cin, input_string); 
+    
+    cout << "Hello, World." << endl;
+    
+    cout << input_string << endl;
+
+
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-1.cpp b/30 days of code Solutions/Day-1.cpp
new file mode 100644
index 0000000..07eb71d
--- /dev/null
+++ b/30 days of code Solutions/Day-1.cpp	
@@ -0,0 +1,26 @@
+#include <iostream>
+#include <iomanip>
+#include <limits>
+
+using namespace std;
+
+int main() {
+    int i = 4;
+    double d = 4.0;
+    string s = "HackerRank ";
+    
+//-----------------------------------------------------------------
+
+    
+   int lo;
+   string lo2;
+   double lo3;
+    cin >> lo >> lo3 >> lo2;
+    
+    cout << lo + i << endl;
+    cout <<  lo3 + d << endl;
+    cout << s << lo2 << endl;
+    
+//---------------------------------------------------------------------
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-10.cpp b/30 days of code Solutions/Day-10.cpp
new file mode 100644
index 0000000..a317b63
--- /dev/null
+++ b/30 days of code Solutions/Day-10.cpp	
@@ -0,0 +1,32 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+#include <bitset>
+
+using namespace std;
+
+bool desc(int i, int l){return (i > l);}
+
+int main(){
+    int n;
+    cin >> n;
+    vector<int> ones;
+    bitset<32> m(n);
+    string ip = m.to_string();
+    int cnt = 0;
+    for(int m = 0; m < ip.size(); ++m){
+        if(ip[m] == '1'){
+            ++cnt;
+        }
+        else{
+            ones.push_back(cnt);
+            cnt = 0;
+        }
+        if(m == ip.size() - 1){
+            ones.push_back(cnt);
+        }
+    }
+    sort(ones.begin(), ones.end(), desc);
+    cout << ones.at(0) << endl;
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-11.cpp b/30 days of code Solutions/Day-11.cpp
new file mode 100644
index 0000000..e89669c
--- /dev/null
+++ b/30 days of code Solutions/Day-11.cpp	
@@ -0,0 +1,41 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+vector<vector<int> >lmao;
+vector<int> answers;
+
+bool desc(int i, int k){return i > k;}
+
+int TakeInput(int i, int m)
+{
+	for(int f = 0; f < i; ++f){
+		vector<int> temp;
+		for(int a = 0; a < m; ++a){
+			int x;
+			cin >> x;
+			temp.push_back(x);
+		}
+		lmao.push_back(temp);
+	}
+	return 0;
+}
+
+void compute()
+{
+	for(int i = 0; i < lmao.size() - 2; ++i){
+		for(int e = 0; e < lmao[i].size() - 2; ++e){
+			int sum = lmao[i][e] + lmao[i][e+1] + lmao[i][e+2] + lmao[i+1][e+1] +lmao[i+2][e] + lmao[i+2][e+1] + lmao[i+2][e+2];
+			answers.push_back(sum);
+		}
+	}
+}
+int main()
+{
+	TakeInput(6, 6);
+	compute();
+	sort(answers.begin(), answers.end(), desc);
+	cout << answers.at(0) << endl;
+}
diff --git a/30 days of code Solutions/Day-12.cpp b/30 days of code Solutions/Day-12.cpp
new file mode 100644
index 0000000..537fa38
--- /dev/null
+++ b/30 days of code Solutions/Day-12.cpp	
@@ -0,0 +1,78 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+
+class Person{
+	protected:
+		string firstName;
+		string lastName;
+		int id;
+	public:
+		Person(string firstName, string lastName, int identification){
+			this->firstName = firstName;
+			this->lastName = lastName;
+			this->id = identification;
+		}
+		void printPerson(){
+			cout<< "Name: "<< lastName << ", "<< firstName <<"\nID: "<< id << "\n"; 
+		}
+	
+};
+
+//-------------------------------------------------------------------------
+
+class Student :  public Person{
+    private:
+        vector<int> testScores;  
+    public:
+        Student(string firstName, string lastName, int identification, vector<int> scores) : Person(firstName, lastName, identification), testScores(scores) { }   
+
+        char calculate() {
+            int average = 0;
+            for(int i = 0; i < testScores.size(); i++) {
+                average += testScores[i];
+            }
+            average = average / testScores.size();
+
+            if(average >= 90) {
+                return 'O'; // Outstanding
+            }
+            else if(average >= 80) {
+                return 'E'; // Exceeds Expectations
+            }
+            else if(average >= 70) {
+                return 'A'; // Acceptable
+            }
+            else if(average >= 55) {
+                return 'P'; // Poor
+            }
+            else if(average >= 40) {
+                return 'D'; // Dreadful
+            }
+            else {
+                return 'T'; // Troll
+            }
+        }
+};
+
+//-------------------------------------------------------------------------
+
+int main() {
+	string firstName;
+  	string lastName;
+	int id;
+  	int numScores;
+	cin >> firstName >> lastName >> id >> numScores;
+  	vector<int> scores;
+  	for(int i = 0; i < numScores; i++){
+	  	int tmpScore;
+	  	cin >> tmpScore;
+		scores.push_back(tmpScore);
+	}
+	Student* s = new Student(firstName, lastName, id, scores);
+	s->printPerson();
+	cout << "Grade: " << s->calculate() << "\n";
+	return 0;
+}
diff --git a/30 days of code Solutions/Day-13.cpp b/30 days of code Solutions/Day-13.cpp
new file mode 100644
index 0000000..28aaadb
--- /dev/null
+++ b/30 days of code Solutions/Day-13.cpp	
@@ -0,0 +1,46 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+#include <string>
+using namespace std;
+class Book{
+    protected:
+        string title;
+        string author;
+    public:
+        Book(string t,string a){
+            title=t;
+            author=a;
+        }
+        virtual void display()=0;
+
+};
+
+//--------------------------------------------------------------------
+
+class MyBook : public Book {
+    protected:
+    int price;
+    public:
+    MyBook(string title, string author, int price) : Book(title, author), price(price) { }
+    void display(){
+        cout << "Title: " << title << endl;
+        cout << "Author: " << author << endl;
+        cout << "Price: " << price << endl;
+    }
+};
+
+//---------------------------------------------------------------------
+
+int main() {
+    string title,author;
+    int price;
+    getline(cin,title);
+    getline(cin,author);
+    cin>>price;
+    MyBook novel(title,author,price);
+    novel.display();
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-14.cpp b/30 days of code Solutions/Day-14.cpp
new file mode 100644
index 0000000..1bfe740
--- /dev/null
+++ b/30 days of code Solutions/Day-14.cpp	
@@ -0,0 +1,48 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+
+using namespace std;
+
+class Difference {
+    private:
+    vector<int> elements;
+  
+  	public:
+  	int maximumDifference;
+    
+//------------------------------------------------------------------------------------
+
+	Difference(vector<int> elm) : elements(elm) {}
+    void computeDifference(){
+        sort(elements.begin(), elements.end(), greater<int>());
+        maximumDifference = elements.at(0) - elements.at(elements.size() - 1);
+    }
+    
+//--------------------------------------------------------------------------------------
+
+}; // End of Difference class
+
+int main() {
+    int N;
+    cin >> N;
+    
+    vector<int> a;
+    
+    for (int i = 0; i < N; i++) {
+        int e;
+        cin >> e;
+        
+        a.push_back(e);
+    }
+    
+    Difference d(a);
+    
+    d.computeDifference();
+    
+    cout << d.maximumDifference;
+    
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-15.cpp b/30 days of code Solutions/Day-15.cpp
new file mode 100644
index 0000000..9242a58
--- /dev/null
+++ b/30 days of code Solutions/Day-15.cpp	
@@ -0,0 +1,60 @@
+#include <iostream>
+#include <cstddef>
+using namespace std;	
+class Node
+{
+    public:
+        int data;
+        Node *next;
+        Node(int d){
+            data=d;
+            next=NULL;
+        }
+};
+class Solution{
+    public:        
+    
+//------------------------------------------------------------
+
+      Node* insert(Node *head,int data)
+      {
+          if(head == NULL){
+              head = new Node(data);
+              return head;
+          }
+          else if(head->next == NULL){
+              Node *temp = new Node(data);
+              head->next = temp;
+              return head;
+          }
+          else{
+              insert(head->next, data);
+          }
+          return head;
+      }
+      
+//--------------------------------------------------------------
+
+      void display(Node *head)
+      {
+          Node *start=head;
+          while(start)
+          {
+              cout<<start->data<<" ";
+              start=start->next;
+          }
+      }
+};
+int main()
+{
+	Node* head=NULL;
+  	Solution mylist;
+    int T,data;
+    cin>>T;
+    while(T-->0){
+        cin>>data;
+        head=mylist.insert(head,data);
+    }	
+	mylist.display(head);
+		
+}
diff --git a/30 days of code Solutions/Day-16.cpp b/30 days of code Solutions/Day-16.cpp
new file mode 100644
index 0000000..a6107d7
--- /dev/null
+++ b/30 days of code Solutions/Day-16.cpp	
@@ -0,0 +1,18 @@
+#include <iostream>
+
+using namespace std;
+
+
+int main(){
+    string S;
+    cin >> S;
+    try{
+        int no;
+        no = stoi(S);
+        cout << no << endl;
+    }
+    catch(exception e){
+        cout << "Bad String" << endl;
+    }
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-17.cpp b/30 days of code Solutions/Day-17.cpp
new file mode 100644
index 0000000..71714b5
--- /dev/null
+++ b/30 days of code Solutions/Day-17.cpp	
@@ -0,0 +1,41 @@
+#include <cmath>
+#include <iostream>
+#include <exception>
+#include <stdexcept>
+using namespace std;
+
+//------------------------------------------------------------------
+
+class Calculator{
+    public:
+    int power(int a, int b){
+        if(a < 0){
+            throw invalid_argument( "n and p should be non-negative" );
+        }
+        if(b < 0){
+            throw invalid_argument( "n and p should be non-negative" );
+        }
+        return pow(a, b);
+    }
+};
+
+//---------------------------------------------------------------------
+
+int main()
+{
+    Calculator myCalculator=Calculator();
+    int T,n,p;
+    cin>>T;
+    while(T-->0){
+      if(scanf("%d %d",&n,&p)==2){
+         try{
+               int ans=myCalculator.power(n,p);
+               cout<<ans<<endl; 
+         }
+         catch(exception& e){
+             cout<<e.what()<<endl;
+         }
+      }
+    }
+    
+}
diff --git a/30 days of code Solutions/Day-18.cpp b/30 days of code Solutions/Day-18.cpp
new file mode 100644
index 0000000..d18b55b
--- /dev/null
+++ b/30 days of code Solutions/Day-18.cpp	
@@ -0,0 +1,29 @@
+#include <iostream>
+#include <vector>
+#include <deque>
+
+using namespace std;
+
+class Solution {
+    private:
+    vector<char>stack;
+    deque<char>queue;
+    int p = 0;
+    int q = 0;
+    public:
+    char pushCharacter(char c){
+       stack.push_back(c);
+       return NULL;
+    }
+    char enqueueCharacter(char c){
+        queue.push_front(c);
+        return NULL;
+    }
+    char popCharacter(){
+        return stack[p++];
+    }
+    char dequeueCharacter(){
+        return queue[q++];
+    }
+
+};
diff --git a/30 days of code Solutions/Day-19.cpp b/30 days of code Solutions/Day-19.cpp
new file mode 100644
index 0000000..0958735
--- /dev/null
+++ b/30 days of code Solutions/Day-19.cpp	
@@ -0,0 +1,41 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+#include <string>
+using namespace std;
+class AdvancedArithmetic{
+    public:
+        virtual int divisorSum(int n)=0;
+};
+
+//--------------------------------------------------------------------
+
+class Calculator : public AdvancedArithmetic{
+    public:
+    int divisorSum(int n){
+        vector<int>divisors;
+        for(int i = 1; i <= n; ++i){
+            if(n % i == 0){
+                divisors.push_back(i);
+            }
+        }
+        int sum = 0;
+        for(auto m : divisors){
+            sum += m;
+        }
+        return sum;
+    }
+};
+
+//---------------------------------------------------------------
+
+int main(){
+    int n;
+    cin >> n;
+    AdvancedArithmetic *myCalculator = new Calculator(); 
+    int sum = myCalculator->divisorSum(n);
+    cout << "I implemented: AdvancedArithmetic\n" << sum;
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-2.cpp b/30 days of code Solutions/Day-2.cpp
new file mode 100644
index 0000000..1fe2fce
--- /dev/null
+++ b/30 days of code Solutions/Day-2.cpp	
@@ -0,0 +1,14 @@
+#include <iostream>
+using namespace std;
+
+
+int main() {
+    double x, y, z;
+    cin >> x >> y >> z;
+    double tip = x * y / 100;
+    double tax = x * z / 100;
+    double total = x + tip + tax;
+    int total2 = total;
+    cout << "The total meal cost is " << total2 << " dollars.";
+    
+}
diff --git a/30 days of code Solutions/Day-20.cpp b/30 days of code Solutions/Day-20.cpp
new file mode 100644
index 0000000..ddf9719
--- /dev/null
+++ b/30 days of code Solutions/Day-20.cpp	
@@ -0,0 +1,40 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+
+int calculate(vector<int> &ab)
+{
+	int allswaps = 0;
+	while(1){
+		int tempswaps = 0;
+		for(int i = 0; i < ab.size() - 1; ++i){
+			if(ab[i] > ab[i+1]){
+				swap(ab[i], ab[i+1]);
+				++tempswaps;
+			}
+		}
+		if(tempswaps == 0){
+			break;
+		}
+		allswaps += tempswaps;
+	}
+	return allswaps;
+}
+
+int main()
+{
+    int n;
+    cin >> n;
+    vector<int> a;
+    for(int a_i = 0;a_i < n;a_i++){
+       int p;
+       cin >> p;
+       a.push_back(p);
+    }
+    cout << "Array is sorted in " << calculate(a) << " swaps." << endl;
+    cout << "First Element: " << a.at(0) << endl;
+    cout << "Last Element: " << a.at(a.size() - 1) << endl;
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-21.cpp b/30 days of code Solutions/Day-21.cpp
new file mode 100644
index 0000000..f26aa90
--- /dev/null
+++ b/30 days of code Solutions/Day-21.cpp	
@@ -0,0 +1,26 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+//---------------------------------------------------------
+
+template<typename TP> 
+void printArray(vector<TP> array) {
+     for(TP i : array){
+          cout << i << endl;
+     }
+}
+
+//-----------------------------------------------------
+
+int main() {
+  
+    vector<int> vInt{1, 2, 3};
+    vector<string> vString{"Hello", "World"};
+    
+    printArray<int>(vInt);
+    printArray<string>(vString);
+    
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-22.cpp b/30 days of code Solutions/Day-22.cpp
new file mode 100644
index 0000000..d5b3a16
--- /dev/null
+++ b/30 days of code Solutions/Day-22.cpp	
@@ -0,0 +1,75 @@
+#include <iostream>
+#include <cstddef>
+
+using namespace std;	
+
+class Node{
+    public:
+        int data;
+        Node *left;
+        Node *right;
+        Node(int d){
+            data = d;
+            left = NULL;
+            right = NULL;
+        }
+};
+class Solution{
+    public:
+  		Node* insert(Node* root, int data) {
+            if(root == NULL) {
+                return new Node(data);
+            }
+            else {
+                Node* cur;
+                if(data <= root->data){
+                    cur = insert(root->left, data);
+                    root->left = cur;
+                }
+                else{
+                    cur = insert(root->right, data);
+                    root->right = cur;
+               }
+
+               return root;
+           }
+        }
+        
+//---------------------------------------------------------------------
+
+		int getHeight(Node* root){
+          if(root == NULL){
+              return -1;
+          }
+          int ldepth = getHeight(root->left);
+          int rdepth = getHeight(root->right);
+          if(ldepth < rdepth){
+              return (rdepth + 1);
+          }else {return ldepth +1;}
+        }
+
+//-----------------------------------------------------------------
+
+}; //End of Solution
+
+int main() {
+    Solution myTree;
+    Node* root = NULL;
+    int t;
+    int data;
+
+    cin >> t;
+
+    while(t-- > 0){
+        cin >> data;
+        root = myTree.insert(root, data);
+    }
+    int height = myTree.getHeight(root);
+    cout << height;
+
+    return 0;
+}
+    
+       
+            
+        
diff --git a/30 days of code Solutions/Day-23.cpp b/30 days of code Solutions/Day-23.cpp
new file mode 100644
index 0000000..96266dd
--- /dev/null
+++ b/30 days of code Solutions/Day-23.cpp	
@@ -0,0 +1,80 @@
+#include <iostream>
+#include <cstddef>
+#include <queue>
+#include <string>
+#include <cstdlib>
+
+using namespace std;	
+class Node{
+    public:
+        int data;
+        Node *left,*right;
+        Node(int d){
+            data=d;
+            left=right=NULL;
+        }
+};
+class Solution{
+    public:
+  		Node* insert(Node* root, int data){
+            if(root==NULL){
+                return new Node(data);
+            }
+            else{
+                Node* cur;
+                if(data<=root->data){
+                    cur=insert(root->left,data);
+                    root->left=cur;
+                }
+                else{
+                   cur=insert(root->right,data);
+                   root->right=cur;
+                 }           
+           return root;
+           }
+        }
+        
+//-----------------------------------------------------------------------------------
+
+	void levelOrder(Node *root){
+      int height = MaxHeight(root);
+        for(int i = 0; i <= height; ++i){
+            ThisLevelTransversal(root, i);
+        }
+	}
+    int MaxHeight(Node* root){
+          if(root == NULL){
+              return -1;
+          }
+          int ldepth = MaxHeight(root->left);
+          int rdepth = MaxHeight(root->right);
+          if(ldepth < rdepth){
+              return (rdepth + 1);
+          }else {return ldepth +1;}
+        }
+    void ThisLevelTransversal(Node *root, int level){
+        if(root == NULL){return;}
+        if (level == 0){
+            cout << root->data << " ";
+        }else if (level > 0){
+            ThisLevelTransversal(root->left, level-1);
+            ThisLevelTransversal(root->right, level-1);
+        }
+        
+    }
+    
+//-------------------------------------------------------
+
+};//End of Solution
+int main(){
+    Solution myTree;
+    Node* root=NULL;
+    int T,data;
+    cin>>T;
+    while(T-->0){
+        cin>>data;
+        root= myTree.insert(root,data);
+    }
+    myTree.levelOrder(root);
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-24.cpp b/30 days of code Solutions/Day-24.cpp
new file mode 100644
index 0000000..6f4b3b1
--- /dev/null
+++ b/30 days of code Solutions/Day-24.cpp	
@@ -0,0 +1,89 @@
+#include <cstddef>
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;	
+class Node
+{
+    public:
+        int data;
+        Node *next;
+        Node(int d){
+            data=d;
+            next=NULL;
+        }
+};
+class Solution{
+    public:        
+    
+//----------------------------------------------------------------------
+
+          Node* removeDuplicates(Node *head)
+          {
+           Node *cur = head;
+              Node *helper;
+              if(cur == NULL){
+                  return head;
+              }
+              while(cur->next != NULL){
+                  if(cur->data == cur->next->data){
+                      cur->next = cur->next->next;
+                  }
+                  else cur = cur->next;
+              }
+              return head;
+           }
+           
+//---------------------------------------------------------------------------
+
+          Node* insert(Node *head,int data)
+          {
+               Node* p=new Node(data);
+               if(head==NULL){
+                   head=p;  
+
+               }
+               else if(head->next==NULL){
+                   head->next=p;
+
+               }
+               else{
+                   Node *start=head;
+                   while(start->next!=NULL){
+                       start=start->next;
+                   }
+                   start->next=p;   
+
+               }
+                    return head;
+                
+            
+          }
+          void display(Node *head)
+          {
+                  Node *start=head;
+                    while(start)
+                    {
+                        cout<<start->data<<" ";
+                        start=start->next;
+                    }
+           }
+};
+			
+int main()
+{
+	Node* head=NULL;
+  	Solution mylist;
+    int T,data;
+    cin>>T;
+    while(T-->0){
+        cin>>data;
+        head=mylist.insert(head,data);
+    }	
+    head=mylist.removeDuplicates(head);
+
+	mylist.display(head);
+		
+}
diff --git a/30 days of code Solutions/Day-25.cpp b/30 days of code Solutions/Day-25.cpp
new file mode 100644
index 0000000..a0bea8f
--- /dev/null
+++ b/30 days of code Solutions/Day-25.cpp	
@@ -0,0 +1,33 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+bool CheckPrime(int n){
+    if(n == 1){return false;}
+    int m;
+    m = sqrt(n);
+    bool isprime = true;
+    for(int i = 2; i <= m; ++i){
+        if(n % i == 0){
+            isprime = false;
+            break;
+        }
+    }
+    return isprime;
+}
+
+int main() {
+    int p;
+    cin >> p;
+    for(int i = 0; i < p; ++i){
+        int m;
+        cin >> m;
+        if(CheckPrime(m)){
+            cout << "Prime" << endl;
+        }else cout << "Not prime" << endl;
+    }
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-26.cpp b/30 days of code Solutions/Day-26.cpp
new file mode 100644
index 0000000..812cc15
--- /dev/null
+++ b/30 days of code Solutions/Day-26.cpp	
@@ -0,0 +1,28 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+
+int main() {
+    int fine;
+    int retDay, retMonth, retYear;
+    int expDay, expMonth, expYear;
+        cin >> retDay >> retMonth >> retYear;
+        cin >> expDay >> expMonth >> expYear;
+    if(retYear < expYear){
+        fine = 0;
+    }else if(retYear == expYear){
+        if(retMonth < expMonth){
+            fine = 0;
+        }else if(retMonth == expMonth){
+            if(retDay <= expDay){
+                fine = 0;
+            }else fine = (retDay - expDay) * 15;
+        }else fine = (retMonth - expMonth) * 500;
+    }else fine = 10000;
+    cout << fine << endl;
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-27.cpp b/30 days of code Solutions/Day-27.cpp
new file mode 100644
index 0000000..ba6f790
--- /dev/null
+++ b/30 days of code Solutions/Day-27.cpp	
@@ -0,0 +1,106 @@
+#include <algorithm>
+#include <iostream>
+#include <stdexcept>
+#include <vector>
+#include <cassert>
+#include <set>
+
+using namespace std;
+
+int minimum_index(vector<int> seq) {
+    if (seq.empty()) {
+        throw invalid_argument("Cannot get the minimum value index from an empty sequence");
+    }
+    int min_idx = 0;
+    for (int i = 1; i < seq.size(); ++i) {
+        if (seq[i] < seq[min_idx]) {
+            min_idx = i;
+        }
+    }
+    return min_idx;
+}
+
+class TestDataEmptyArray {
+public:
+    static vector<int> get_array() {
+        // complete this function
+          vector<int> v;
+        return v;
+    }
+
+};
+
+class TestDataUniqueValues {
+public:
+    static vector<int> get_array() {
+        // complete this function
+      vector<int> v={1,2,3};
+        return v;
+    }
+
+    static int get_expected_result() {
+        // complete this function
+        return 0;
+    }
+
+};
+
+class TestDataExactlyTwoDifferentMinimums {
+public:
+    static vector<int> get_array() {
+        // complete this function
+        vector<int> v={1,1,2,3};
+        return v;
+        
+    }
+
+    static int get_expected_result() {
+        // complete this function
+        return 0;
+    }
+
+};
+
+
+void TestWithEmptyArray() {
+    try {
+        auto seq = TestDataEmptyArray::get_array();
+        auto result = minimum_index(seq);
+    } catch (invalid_argument& e) {
+        return;
+    }
+    assert(false);
+}
+
+void TestWithUniqueValues() {
+    auto seq = TestDataUniqueValues::get_array();
+    assert(seq.size() >= 2);
+
+    assert(set<int>(seq.begin(), seq.end()).size() == seq.size());
+
+    auto expected_result = TestDataUniqueValues::get_expected_result();
+    auto result = minimum_index(seq);
+    assert(result == expected_result);
+}
+
+void TestWithExactlyTwoDifferentMinimums() {
+    auto seq = TestDataExactlyTwoDifferentMinimums::get_array();
+    assert(seq.size() >= 2);
+
+    auto tmp = seq;
+    sort(tmp.begin(), tmp.end());
+    assert(tmp[0] == tmp[1] and (tmp.size() == 2 or tmp[1] < tmp[2]));
+
+    auto expected_result = TestDataExactlyTwoDifferentMinimums::get_expected_result();
+    auto result = minimum_index(seq);
+    assert(result == expected_result);
+}
+
+int main() {
+    TestWithEmptyArray();
+    TestWithUniqueValues();
+    TestWithExactlyTwoDifferentMinimums();
+    cout << "OK" << endl;
+    return 0;
+}
+
diff --git a/30 days of code Solutions/Day-28.cpp b/30 days of code Solutions/Day-28.cpp
new file mode 100644
index 0000000..99a536a
--- /dev/null
+++ b/30 days of code Solutions/Day-28.cpp	
@@ -0,0 +1,38 @@
+#include <iostream>
+#include <vector>
+#include <string>
+#include <algorithm>
+
+using namespace std;
+
+vector<string>sorted;
+
+bool ascending(string i, string m){return i < m;}
+
+void compute(vector<string> email, vector<string> name){
+    for(int i = 0; i < email.size(); ++i){
+        if(email[i].find("@gmail.com") != std::string::npos){
+            sorted.push_back(name[i]);
+        }
+    }
+    sort(sorted.begin(), sorted.end(), ascending);
+}
+
+int main(){
+    vector<string>mails;
+    vector<string>names;
+    int N;
+    cin >> N;
+    for(int a0 = 0; a0 < N; a0++){
+        string firstName;
+        string emailID;
+        cin >> firstName >> emailID;
+        names.push_back(firstName);
+        mails.push_back(emailID);
+    }
+    compute(mails, names);
+    for(auto m : sorted){
+        cout << m << endl;
+    }
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-29.cpp b/30 days of code Solutions/Day-29.cpp
new file mode 100644
index 0000000..235896a
--- /dev/null
+++ b/30 days of code Solutions/Day-29.cpp	
@@ -0,0 +1,33 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+int outAnd(int a, int b){
+    vector<int>lol;
+    for(int i = 1; i <= a; ++i){
+        lol.push_back(i);
+    }
+    int max = 0;
+    for(int i = 0; i < lol.size(); ++i){
+        for(int p = i + 1; p < lol.size(); ++p){
+            int anded = lol[i] & lol[p];
+            if((anded > max) && (anded < b) ){
+                max =  anded;
+            }
+        }
+    }
+    return max;
+}
+
+int main(){
+    int t;
+    cin >> t;
+    for(int a0 = 0; a0 < t; a0++){
+        int n;
+        int k;
+        cin >> n >> k;
+        cout << outAnd(n, k) << endl;
+    }
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-3.cpp b/30 days of code Solutions/Day-3.cpp
new file mode 100644
index 0000000..fc374f3
--- /dev/null
+++ b/30 days of code Solutions/Day-3.cpp	
@@ -0,0 +1,12 @@
+#include <iostream>
+using namespace std;
+
+
+int main(){
+    int N;
+    cin >> N;
+    if(N%2 != 0 || (N%2 == 0) && N >= 6 && N <= 20){
+        cout << "Weird" << endl;
+    }else cout << "Not Weird" << endl;
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-4.cpp b/30 days of code Solutions/Day-4.cpp
new file mode 100644
index 0000000..b6b53ab
--- /dev/null
+++ b/30 days of code Solutions/Day-4.cpp	
@@ -0,0 +1,56 @@
+using namespace std;
+#include <iostream>
+
+//--------------------------------------------------------------------------------------------------
+
+class Person{
+    public:
+        int age;
+        Person(int initialAge);
+        void amIOld();
+        void yearPasses();
+    };
+
+    Person::Person(int initialAge){
+       if(initialAge < 0){
+           age = 0;
+           cout << "Age is not valid, setting age to 0." << endl;
+       }else age = initialAge;
+
+    }
+
+    void Person::amIOld(){
+        if(age < 13){
+            cout << "You are young." << endl;
+        }
+        else if(age >= 13 && age < 18){
+            cout << "You are a teenager." << endl;
+        }else cout << "You are old." << endl;
+
+    }
+
+    void Person::yearPasses(){
+        age += 1;
+
+    }
+    
+//-------------------------------------------------------------------------
+
+int main(){
+    int t;
+	int age;
+    cin >> t;
+    for(int i=0; i < t; i++) {
+    	cin >> age;
+        Person p(age);
+        p.amIOld();
+        for(int j=0; j < 3; j++) {
+        	p.yearPasses(); 
+        }
+        p.amIOld();
+      
+		cout << '\n';
+    }
+
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-5.cpp b/30 days of code Solutions/Day-5.cpp
new file mode 100644
index 0000000..e19d585
--- /dev/null
+++ b/30 days of code Solutions/Day-5.cpp	
@@ -0,0 +1,13 @@
+#include <iostream>
+
+using namespace std;
+
+
+int main(){
+    int n;
+    cin >> n;
+    for(int i = 1; i <= 10; ++i){
+        cout << n << " x " << i << " = " << n * i << endl;
+    }
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-6.cpp b/30 days of code Solutions/Day-6.cpp
new file mode 100644
index 0000000..1396941
--- /dev/null
+++ b/30 days of code Solutions/Day-6.cpp	
@@ -0,0 +1,22 @@
+#include <iostream>
+#include <string>
+using namespace std;
+
+
+int main() {
+    int n;
+    cin >> n;
+    for(int i = 0; i < n; ++i){
+        string m;
+        cin >> m;
+        for(int k = 0; k < m.size(); k +=2){
+            cout << m[k];
+        }
+        cout << " ";
+        for(int t = 1; t < m.size(); t +=2){
+            cout << m[t];
+        }
+        cout << endl;
+    }
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-7.cpp b/30 days of code Solutions/Day-7.cpp
new file mode 100644
index 0000000..e6f2a96
--- /dev/null
+++ b/30 days of code Solutions/Day-7.cpp	
@@ -0,0 +1,19 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+
+int main(){
+    int n;
+    cin >> n;
+    vector<int> arr(n);
+    for(int arr_i = 0;arr_i < n;arr_i++){
+       cin >> arr[arr_i];
+    }
+    for (int i = arr.size() - 1; i >= 0; --i){
+        cout << arr[i] << " ";
+    }
+    cout << endl;
+    return 0;
+}
diff --git a/30 days of code Solutions/Day-8.cpp b/30 days of code Solutions/Day-8.cpp
new file mode 100644
index 0000000..b15deba
--- /dev/null
+++ b/30 days of code Solutions/Day-8.cpp	
@@ -0,0 +1,25 @@
+#include <iostream>
+#include <vector>
+#include <string>
+using namespace std;
+
+
+int main() {
+    int x;
+    cin >> x;
+    map<string, string> all;
+    for(int i = 0; i < x; ++i){
+        string s, p;
+        cin >> s >> p;
+        all[s] = p;
+    }
+    string h;
+    while(cin >> h){
+        if(all.find(h) == all.end()){
+            cout << "Not found" << endl;
+        }
+        else{
+            cout << h << "=" << all.at(h) << endl;
+        }
+    }
+}
diff --git a/30 days of code Solutions/Day-9.cpp b/30 days of code Solutions/Day-9.cpp
new file mode 100644
index 0000000..91b41fe
--- /dev/null
+++ b/30 days of code Solutions/Day-9.cpp	
@@ -0,0 +1,20 @@
+#include <iostream>
+
+using namespace std;
+
+int factorial(int y)
+{
+    if (y == 1){
+        return 1;
+    }
+    else{
+        return y * factorial(y - 1);
+    }
+}
+
+int main() {
+    int x;
+    cin >> x;
+    cout << factorial(x) << endl;
+    return 0;
+}