@@ -0,0 +1,38 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+// Lets make a function to print map and getting its size
+
+void print(unordered_map<int,string> &m)
+{
+cout<<"Size of the map is "<<m.size()<<endl;
+for (auto pr :m)
+cout<<pr.first<<" "<<pr.second<<" "<<endl;
+}
+
+int main ()
+{
+// 1. inbuilt impletation : It uses hash table it dont uses trees like map // here keys will make hash value
+// 2. Time complexity : O(1)-> Insertion and access
+// 3. valid keys datatypes : we cant keep all type of data types like pair of pair
+// we can use int double string float ... cz these all have possible hash value
+unordered_map<int,string>m;
+// unordered map does not store in sorted manner it will print randomly
+
+m[8]="Shivendra"; // insertion takes O(1)
+m[3]="abc";
+m[5]="cdc";
+m.insert({1,"shiv"});
+/*map<int,string>:: iterator it;
+for (it=m.begin();it!=m.end();++it)
+{
+cout<<it->first<<" "<<it->second<<" "<<endl; // it will give the sorted output
+}*/
+/*m.find // O(1)
+m.earese// o(1)*/
+for (auto &pr :m){
+cout<<pr.first<<" "<<pr.second<<" "<<endl;
+// this will also work as same like above commented code
+
+}
+}