Added MAP in C++

README.md

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 # STL
-Learn STL in C++
+Beginner friendly Repository to contribute and learn STL

Unordered Map of Pairs in C++.cpp

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+// CPP program to demonstrate implementation of
+// unordered_map for a pair.
+#include <bits/stdc++.h>
+using namespace std;
+
+// A hash function used to hash a pair of any kind
+struct hash_pair {
+	template <class T1, class T2>
+	size_t operator()(const pair<T1, T2>& p) const
+	{
+		auto hash1 = hash<T1>{}(p.first);
+		auto hash2 = hash<T2>{}(p.second);
+		return hash1 ^ hash2;
+	}
+};
+
+int main()
+{
+	// Sending the hash function as a third argument
+	unordered_map<pair<int, int>, bool, hash_pair> um;
+
+	// Creating some pairs to be used as keys
+	pair<int, int> p1(1000, 2000);
+	pair<int, int> p2(2000, 3000);
+	pair<int, int> p3(2005, 3005);
+
+	// Inserting values in the unordered_map.
+	um[p1] = true;
+	um[p2] = false;
+	um[p3] = true;
+
+	cout << "Contents of the unordered_map : \n";
+	for (auto p : um)
+		cout << "[" << (p.first).first << ", "
+			<< (p.first).second << "] ==> "
+			<< p.second << "\n";
+
+	return 0;
+}

map.cpp

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+#include <iostream> 
+#include <iterator> 
+#include <map> 
+
+using namespace std; 
+
+int main() 
+{ 
+
+	// empty map container 
+	map<int, int> gquiz1; 
+
+	// insert elements in random order 
+	gquiz1.insert(pair<int, int>(1, 40)); 
+	gquiz1.insert(pair<int, int>(2, 30)); 
+	gquiz1.insert(pair<int, int>(3, 60)); 
+	gquiz1.insert(pair<int, int>(4, 20)); 
+	gquiz1.insert(pair<int, int>(5, 50)); 
+	gquiz1.insert(pair<int, int>(6, 50)); 
+	gquiz1.insert(pair<int, int>(7, 10)); 
+
+	// printing map gquiz1 
+	map<int, int>::iterator itr; 
+	cout << "\nThe map gquiz1 is : \n"; 
+	cout << "\tKEY\tELEMENT\n"; 
+	for (itr = gquiz1.begin(); itr != gquiz1.end(); ++itr) { 
+		cout << '\t' << itr->first 
+			<< '\t' << itr->second << '\n'; 
+	} 
+	cout << endl; 
+
+	// assigning the elements from gquiz1 to gquiz2 
+	map<int, int> gquiz2(gquiz1.begin(), gquiz1.end()); 
+
+	// print all elements of the map gquiz2 
+	cout << "\nThe map gquiz2 after"
+		<< " assign from gquiz1 is : \n"; 
+	cout << "\tKEY\tELEMENT\n"; 
+	for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { 
+		cout << '\t' << itr->first 
+			<< '\t' << itr->second << '\n'; 
+	} 
+	cout << endl; 
+
+	// remove all elements up to 
+	// element with key=3 in gquiz2 
+	cout << "\ngquiz2 after removal of"
+			" elements less than key=3 : \n"; 
+	cout << "\tKEY\tELEMENT\n"; 
+	gquiz2.erase(gquiz2.begin(), gquiz2.find(3)); 
+	for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { 
+		cout << '\t' << itr->first 
+			<< '\t' << itr->second << '\n'; 
+	} 
+
+	// remove all elements with key = 4 
+	int num; 
+	num = gquiz2.erase(4); 
+	cout << "\ngquiz2.erase(4) : "; 
+	cout << num << " removed \n"; 
+	cout << "\tKEY\tELEMENT\n"; 
+	for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) { 
+		cout << '\t' << itr->first 
+			<< '\t' << itr->second << '\n'; 
+	} 
+
+	cout << endl; 
+
+	// lower bound and upper bound for map gquiz1 key = 5 
+	cout << "gquiz1.lower_bound(5) : "
+		<< "\tKEY = "; 
+	cout << gquiz1.lower_bound(5)->first << '\t'; 
+	cout << "\tELEMENT = "
+		<< gquiz1.lower_bound(5)->second << endl; 
+	cout << "gquiz1.upper_bound(5) : "
+		<< "\tKEY = "; 
+	cout << gquiz1.upper_bound(5)->first << '\t'; 
+	cout << "\tELEMENT = "
+		<< gquiz1.upper_bound(5)->second << endl; 
+
+	return 0; 
+}