Cefalo CodeFiesta 2022 AUST Inter University Programming Contest Problem A K th Permutation Revisited Solution

  

Problem   Creative Kindergarten    Link:  https://drive.google.com/file/d/1iuwkvSfzfyeIjmh_FN9alTTkCd-RaWgC/view

Solution in C++:

///La ilaha illellahu muhammadur rasulullah

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

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

///**********ALLAH IS ALMIGHTY************///

#include<bits/stdc++.h>

using namespace std;

using ll=long long;

int main()

{

    ll t,x=0;

    scanf("%d",&t);

    while(t--)

    {

        x++;

        ll n,m,k;

        scanf("%lld%lld%lld",&n,&k,&m);

        if(m>4)

        {

            ll  nn;

            nn=n-m;

            printf("Case %d: ",x);

            ll ans=( n * ( n + 1 ) / 2 ) - nn * ( nn + 1 ) / 2;

            printf("%lld\n",ans);

            continue;

        }

        vector<ll>v;

        ll  a[]= {n-3,n-2,n-1,n};

        ll  i=0;

        do

        {

            i++;

            if(i==k)

            {

                v.push_back(a[0]);

                v.push_back(a[1]);

                v.push_back(a[2]);

                v.push_back(a[3]);

            }

        }

        while (next_permutation(a, a + 4));

        ll  j=0,s=0;

        for(int i=3 ; i>=0 ; i--)

        {

            j++;

            s+=v[i];

            if(j==m)

                break;

        }

        printf("Case %d: %d\n",x,s);

    }

}