Codeforces Round #605 (Div. 3) 1272C - Yet Another Broken Keyboard Solution

  Problem Link :  https://codeforces.com/problemset/problem/1272/C

Solution in C++:

///La ilaha illellahu muhammadur rasulullah

///******Bismillahir-Rahmanir-Rahim******///

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

#include <bits/stdc++.h>

using namespace std;

int main()

{

    long long n,i,k,sum=0,cn=0;

    map<char,int>mp;

    cin>>n>>k;

    string s;

    char ch;

    cin>>s;

    for(i=0; i<k; i++)

    {

        cin>>ch;

        mp[ch]++;

    }

    for(i=0; i<n; i++)

    {

        if(mp[s[i]]>0)

            cn++;

        else if(cn!=0)

        {

            sum=sum+(cn*(cn+1))/2;

            cn=0;

        }

    }

    cout<<sum+(cn*(cn+1))/2<<endl;

    return 0;

}