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StlTricks

STL Tricks that can be useful​

1. How to use std::vector as a stack​

#include<bits/stdc++.h> 
using namespace std ;

int  main(){

    vector<int> v ;
    v.push_back(1) ;
    v.push_back(2) ;
    v.push_back(3) ;
    v.push_back(4) ;
    v.push_back(5) ;

    cout<<"The stack is : "<<endl ;
    while(!v.empty()){
        cout<<v.back()<<" ";
        v.pop_back() ;
    }
    cout<<endl ;
    return 0 ;

}

2. Sort function with a comparator​

    vector<int> ans;
    // using a lambda function to sort the vector in descending order``
    sort(ans.begin(),ans.end(),[](int a , int b){
            return b < a;
    });

    // without lambda function

    bool compare(int a , int b){
        return b < a ;
    }
    sort(ans.begin(),ans.end(),compare);

    // normal sort function -> sorts in ascending order
    sort(ans.begin(),ans.end());

3. Find sum of a vector using accumulate​

    vector<int> ans;
    int sum = accumulate(ans.begin(),ans.end(),0);

4. Find the maximum element in a vector​

    vector<int> ans;
    int max = *max_element(ans.begin(),ans.end());

5. Find the minimum element in a vector​

    vector<int> ans;
    int min = *min_element(ans.begin(),ans.end());

6. Find the number of elements in a vector​

    vector<int> ans;
    int size = ans.size();