Merge pull request #31 from aviraltandon21/master

Peak element in array

Parenthesis-Checker.cpp

@@ -0,0 +1,70 @@
+#include<bits/stdc++.h>
+#include <iostream>
+
+using namespace std;
+
+// Given an expression string x. Examine whether the pairs and the orders of “{“,”}”,”(“,”)”,”[“,”]” are correct in exp.
+// For example, the function should return 'true' for exp = “[()]{}{[()()]()}” and 'false' for exp = “[(])”.
+bool ispar(string expr)
+{
+
+    stack<char> s; 
+    char x; 
+
+    for (int i = 0; i < expr.length(); i++)  
+    { 
+        if (expr[i] == '(' || expr[i] == '['
+            || expr[i] == '{')  
+        { 
+            s.push(expr[i]); 
+            continue; 
+        } 
+
+        if (s.empty()) 
+            return false; 
+
+        switch (expr[i]) { 
+        case ')': 
+
+            x = s.top(); 
+            s.pop(); 
+            if (x == '{' || x == '[') 
+                return false; 
+            break; 
+
+        case '}': 
+
+            x = s.top(); 
+            s.pop(); 
+            if (x == '(' || x == '[') 
+                return false; 
+            break; 
+
+        case ']': 
+            x = s.top(); 
+            s.pop(); 
+            if (x == '(' || x == '{') 
+                return false; 
+            break; 
+        } 
+    } 
+
+
+    return (s.empty()); 
+
+}
+
+
+
+int main()
+{
+    string s;
+    cin>>s;
+
+    if(ispar(s))
+    cout<<"Balanced"<<endl;
+    else
+    cout<<"Not Balanced"<<endl;
+
+    return 0;
+}

Peak_element.cpp

@@ -0,0 +1,42 @@
+#include<bits/stdc++.h>
+#include <iostream>
+
+using namespace std;
+
+// A peak element in an array is the one that is not smaller than its neighbours.
+// Given an array arr[] of size N, find the index of any one of its peak elements.
+
+int findPeakUtil(int arr[], int low, int high, int n)
+{
+    int mid = low + (high - low) / 2;
+
+    if ((mid == 0 || arr[mid - 1] <= arr[mid]) && (mid == n - 1 || arr[mid + 1] <= arr[mid]))
+        return mid;
+
+    else if (mid > 0 && arr[mid - 1] > arr[mid])
+        return findPeakUtil(arr, low, (mid - 1), n);
+
+    else
+        return findPeakUtil(arr, (mid + 1), high, n);
+}
+
+
+int peakElement(int arr[], int n)
+{
+    return findPeakUtil(arr, 0, n - 1, n);
+
+}
+
+
+int main()
+{
+    int n;
+    cin>>n;
+    int arr[n];
+    for(int i=0;i<n;i++)
+    cin>>arr[i];
+
+    cout<<peakElement(arr,n);
+
+    return 0;
+}