Added Standard Template Library Codes and some basic and interesting questions.

STL 2.0/MAPS/basics.cpp

@@ -0,0 +1,52 @@
+/*
+-------------- ORDERED MAPS -----------------
+Time Complexity : O(log(n))
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+
+void print(map<int,string> &m){
+    cout<<"Size: "<<m.size()<<endl;
+    for(auto &pr : m){
+        cout<<pr.first<<" "<<pr.second<<endl;
+    }
+}
+
+int main(){
+    map<int,string> m;
+    //TIME COMPLEXITY OF INSERTION OF ELEMENTS: O(log(n))--> n: size of MAP
+    m[1] = "abc";
+    m[5] = "cdc";
+    m[3] = "acd";
+    m.insert({4,"abc"});
+    m.insert({8,"abc"});
+
+
+    // map<int,string> :: iterator it;
+    // for(it=m.begin();it!=m.end();it++){
+    //     cout<<it->first<<" "<<it->second<<endl;
+    // }
+
+    print(m);
+
+    //Find function: takes in key value
+    //             : returns an iterator pointing towards the value
+    //TIME COMPLEXITY: O(log(n))
+    // auto it = m.find(9);
+    // if(it == m.end()){
+    //     cout<<"No such value exists"<<endl;
+    // }
+    // else{
+    //     cout<<it->first<<" "<<it->second<<endl;
+    // }
+
+    //ERASE FUNCTION: takes key/iterator as input
+    //              : deletes the specified value if present
+    //TIME COMPLEXITY: O(log(n))
+    // auto it = m.find(3);
+    // m.erase(3);
+    // print(m);
+
+    return 0;
+}

STL 2.0/MAPS/nesting.cpp

@@ -0,0 +1,7 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    map<pair<string,string>,vector<int>> m;
+    return 0;
+}

STL 2.0/MAPS/questions.cpp

@@ -0,0 +1,49 @@
+// // /*
+// // Given N strings. Print unique strings in lexographical order
+// // with their frequency
+// // N<= 10^5
+// // |S| <= 100
+// // */
+
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    int N;cin>>N;
+    map<string,int> m;
+    for(int i=0;i<N;i++){
+        string s;
+        cin>>s;
+        // m[i] = s; //making a map
+        m[s]++;
+    }
+//Range Based Loop
+    for(auto pair : m){
+        cout<<pair.first<<" "<<pair.second<<endl;
+    }
+    return 0;
+}
+
+// // -------- MONK and class MARKS: Hackerearth -----------
+//Please search this question on net for more info
+// #include<bits/stdc++.h>
+// using namespace std;
+
+// int main(){
+//     multimap<int,string> list;
+//     int turn;cin>>turn;
+//     while(turn--){
+//         string name; int marks;
+//         cin>>name>>marks;
+//         list.insert({marks,name});
+//     }
+//     map<int,string> :: iterator it;
+//     it  = (--list.end());
+//     while(it!=list.begin()){
+//         cout<<it->second<<" "<<it->first<<endl;
+//         --it;
+//     }
+//     cout<<it->second<<" "<<it->first<<endl;
+//     return 0;
+// }
+

STL 2.0/MAPS/unordered.cpp

@@ -0,0 +1,21 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    unordered_map<string,int> m;
+    int N;cin>>N;
+    while(N--){
+        string s;
+        cin>>s;
+        m[s]++;
+    }
+    int q;cin>>q;
+    while(q--){
+        string s;
+        cin>>s;
+        cout<<m[s]<<endl;
+    }
+
+
+    return 0;
+}

STL 2.0/SETS/intro.cpp

@@ -0,0 +1,28 @@
+/*
+--------------- ORDERED SET ----------------
+Time Complexity: O(log(n))
+*/
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    set<string> s;
+    s.insert("abc");
+    s.insert("ghi");
+    s.insert("def");
+    s.insert("jkl");
+    s.insert("mnp");
+    s.insert("abcd");
+    s.insert("sdwefd");
+    auto it = s.find("abc");
+    if(it != s.end()){
+        // cout<<*it<<endl;
+        s.erase(it);
+    }
+
+    for(auto val : s){
+        cout<<val<<endl;
+    }
+
+    return 0;
+}

STL 2.0/SETS/questions.cpp

@@ -0,0 +1,86 @@
+//Monk and magical bag question: HACKEREARTH
+// #include<bits/stdc++.h>
+// using namespace std;
+
+// int main(){
+//     int turn;
+//     cin>>turn;
+//     while(turn--){
+//         long long N , K; //N--> number of bag, K--> total time he has
+//         multiset<long long> candies;
+//         for (long long i = 0; i < N; i++)
+//         {
+//             long long A;
+//             cin>>A;
+//             candies.insert(A);
+//         }
+//         long long eaten = 0;
+//         while(K--){
+//             auto last_it = (--candies.end());
+//             long long candy_ct = *(last_it);
+//             eaten += candy_ct;
+//             candies.erase(last_it);
+//             candies.insert(candy_ct / 2);
+//         }
+//         cout<< eaten << endl;   
+//     }
+
+//     return 0;
+// }
+
+// ------------- SETS : Hackerrank ---------------
+// #include<bits/stdc++.h>
+// using namespace std;
+
+// int main(){
+//     int query; cin>>query;
+//     set<long long> s;
+//     while(query--){
+//         long long y,x;
+//         cin>>y>>x;
+//         if(y==1){
+//             s.insert(x);
+//         }
+//         else if(y==2){
+//             auto it = s.find(x);
+//             if(it==s.end()){
+//                 continue;
+//             }
+//             else{
+//                 s.erase(x);
+//             }
+//         }
+//         else if(y==3){
+//             auto it = s.find(x);
+//             if(it !=s.end()){
+//                 cout<<"Yes"<<endl;
+//             }
+//             else{
+//                 cout<<"No"<<endl;
+//             }
+//         }
+//     }
+//     return 0;
+// }   
+
+// ------ MONK BIRTHDAY:Hackerearth -----------
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    int N;cin>>N;
+    while(N--){
+        set<string> list;
+        int num;cin>>num;
+        while(num--){
+            string name;
+            cin>>name;
+            list.insert(name);
+        }
+        for(auto val : list){
+            cout<< val<<endl;
+        }
+        cout<<endl;
+    }
+    return 0;
+}

STL 2.0/SETS/unordered_set.cpp

@@ -0,0 +1,37 @@
+/*
+------------ Time Complexity ----------------
+O(1)
+*/
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    unordered_set<string> s;
+    int N;
+    cin>>N;
+    for (int i = 0; i < N; i++)
+    {
+        string S;
+        cin>>S;
+        s.insert(S);
+    }
+    int Q;
+    cin>>Q;
+    for (int i = 0; i < Q; i++)
+    {
+        string q;
+        cin>>q;
+        auto it  = s.find(q);
+        if(it!=s.end()){
+            cout<<"PRESENT"<<endl;
+        }
+        else{
+            cout<<"NOT PRESENT"<<endl;
+        }
+
+    }
+
+
+
+    return 0;
+}

STL 2.0/Sorting/Upper_Lower_Bound.cpp

@@ -0,0 +1,23 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    int n;cin>>n;
+    int a[n];
+    for(int i = 0;i<n;++i){
+        cin>>a[i];
+    }
+    sort(a,a+n);
+    for(int i = 0;i<n;i++){
+        cout<<a[i]<<" ";
+    }
+    cout<<endl;
+    int *ptr = lower_bound(a,a+n,6);
+    int *ptr2 = upper_bound(a,a+n,25);
+    if(ptr==a+n && ptr2==a+n){
+        cout<<"Not Found"<<endl;
+        return 0;
+    }
+    cout<<(*ptr)<<" "<<(*ptr2)<<endl;
+    return 0;
+}

STL 2.0/Sorting/sort_array.cpp

@@ -0,0 +1,16 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    int size;cin>>size;
+    int a[size];
+    for(int i=0;i<size;i++){
+        cin>>a[i]; 
+    }
+    sort(a,a+size);
+    for(int i=0;i<size;i++){
+        cout<<a[i]<<" ";
+    }
+    cout<<endl;
+    return 0;
+}

STL 2.0/Sorting/sort_vector.cpp

@@ -0,0 +1,16 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    int n;cin>>n;
+    vector<int> a(n);
+    for(int i = 0;i<n;i++){
+        cin>>a[i];
+    }
+    sort(a.begin(),a.end());
+    for(int i = 0;i<n;i++){
+        cout<<a[i]<<" ";
+    }
+    cout<<endl;
+    return 0;
+}

STL 2.0/Stacks & Queues/queue_intro.cpp

@@ -0,0 +1,16 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    queue<string> q;
+    q.push("abc"); //Frontmost element
+    q.push("bcd");
+    q.push("dfr");
+    q.push("wer");
+    q.push("asx");//Last element
+    while(!q.empty()){
+        cout<<q.front()<<" ";
+        q.pop();
+    }
+    return 0;
+}

STL 2.0/Stacks & Queues/stack_intro.cpp

@@ -0,0 +1,15 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int main(){
+    stack<int> s;
+    s.push(2); //First Element
+    s.push(3);
+    s.push(4);
+    s.push(5); //Topmost Element
+    while(!s.empty()){
+        cout<<s.top()<<endl;
+        s.pop();
+    }
+    return 0;
+}