1175D - Array Splitting - CodeForces Solution

// Whatever_it_takes_
// (╯°□°）╯ ヽ(°□°ヽ)
#include"bits/stdc++.h"
using namespace std; 
#define ll long long
#define mod  998244353
void solve(){ 
     ll n,m ;
     cin>>n>>m;
     vector<ll> vk(n);
     for(int i = 0 ;i<n;i++)
      cin>>vk[i];
     vector<ll> suf(n);
     suf[n-1] = vk[n-1];
     for(int i = n-2;i>=0;i--){
         suf[i] = vk[i]+suf[i+1];
     }
     sort(suf.begin()+1,suf.end());
     ll ans = suf[0] ;
     for(int i = n-1;i>(n-1)-(m-1);i--){
         ans += suf[i] ;
     }
     cout<<ans<<endl;
    }

 
int main()
{
    //#ifndef ONLINE_JUDGE
        //freopen("input.txt", "r", stdin);
        //freopen("output.txt", "w", stdout);
   //#endif
    
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t=1  ;
    //cin>>t ;
    while(t--){
     solve() ;
    }
    
    
    return 0;
}