Submission #17763744

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Source Code Expand

#include <bits/stdc++.h>
#define rep(i, n) for (long i = 0; i < (long)(n); i++)
using namespace std;


long getNum(long num, long N){
    return min(num-1, 2*N-num+1);
}

int main(void){
    long N, K;
    cin >> N >> K;
    long num = 0;

    if(K>=0){
        for(long AB = 2*N; AB>=2+K; --AB){
            long CD = AB-K;
            num += getNum(AB, N)*getNum(CD, N);
        }
    }
    else{
        //a+b < c+d
        for(long CD = 2*N; CD>=2-K; --CD){
            long AB = CD+K;
            num += getNum(AB, N)*getNum(CD, N);
        }
    }

    cout << num << endl;
}

Submission Info

Judge Result