Submission #19699685

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

int bmsum(vector<int>& v, long long bm){
  int i = 0;
  int ret = 0;
  while (bm != 0){
    if (bm & 1) ret += v[i];
    i++;
    bm >>= 1;
  }
  return ret;
}

long long h0[4000];
long long h1[4000];
int offset_h = 2000;

int main()
{
  int n, a;
  cin >> n >> a;

  vector<int> v(n);
  for (int i = 0; i < n; i++){
    cin >> v[i];
    v[i] -= a;
  }

  int n0 = n / 2;
  int n1 = n - n0;
  
  long long max_bm0 = (1 << n0) - 1;
  long long max_bm1 = (1 << n1) - 1;
  long long max_bm = (1 << max(n0, n1)) - 1;

  for (long long bm = max_bm; bm >= 0; --bm){
    if (bm <= max_bm0){
      int s = bmsum(v, bm);
      h0[s + offset_h]++;
    }
    if (bm <= max_bm1){
      int s = bmsum(v, bm << n0);
      h1[s + offset_h]++;
    }
  }

  long long ret = -1;

  for (int i = -1500; i < 1500; i++){
    ret += h0[offset_h + i] * h1[offset_h - i];
  }
  
  cout << ret << endl;
  return 0;
}

Submission Info

Judge Result