466C Codeforces - Number of ways

466C Codeforces

Number of ways

Solution in c++

#include <iostream>

#include <numeric>

using namespace std;

   int nn[500001],dp[500001];

int main()

{

   long long n,sum=0;

   cin>>n;

   for(int i=0;i<n;i++){

        cin>>nn[i];

        sum+=nn[i];

   }

   if(sum%3){

    cout<<"0\n";

    return 0;

   }

    long long suf=0,pre=0,sol=0;

   for(int i=n-1;i>=0;i--){

        suf+=nn[i];

        if(i<n-1)dp[i]=dp[i+1];

        else dp[i]=0;

        if(suf==sum/3)dp[i]++;

   }

   for(int i=0;i<n-2;i++){

        pre+=nn[i];

        if(pre==sum/3)sol+=dp[i+2];

   }

    cout<<sol<<"\n";

    return 0;

}

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About Mohamed Sobhi

My name is Mo.Sobhy ,I study at School excelling high school in Ain Shams ,Cairo
My hobbies is programming ,and web development ,playing chess and writing horror stories.