Submission #3777161

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Source Code Expand

#include <cstdio>
#include <vector>
using namespace std;
using ull = unsigned long long;
constexpr int mod = 1000000007;
constexpr int MAX = 4010;

ull comb[MAX][MAX];
void combInit(){
  for(int i = 0; i < MAX; i++)
    comb[i][0] = comb[i][i] = 1;
  for(int i = 2; i < MAX; i++){
    for(int j = 1; j < i; j++){
      comb[i][j] = comb[i-1][j-1]%mod
                  + comb[i-1][j]%mod;
      comb[i][j] %= mod;
    }
  }
}

int main(){
  int n, a, b;
  ull ans = 0;
  scanf("%d", &n);
  vector<int> meat(n), sum(n);
  for(int i = 0; i < n; i++){
    scanf("%d %d", &a, &b);
    meat[i] = a, sum[i] = a+b;
  }
  combInit();
  for(int i = 0; i < n-1; i++){
    for(int j = i+1; j < n; j++){
      ans += comb[sum[i]+sum[j]][meat[i]+meat[j]]%mod;
    }
  }
  printf("%lld\n", ans);
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:24:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
                  ^
./Main.cpp:27:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &a, &b);
                           ^

Judge Result