Submission #3106201

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Source Code Expand

#include <bits/stdc++.h>
#define N 1000000007
using namespace std;

int n, m, q, k, x;
int a[2005] = {0};
// dp[i][j] = combi i:type j:num
int dp[2005][2005] = {0};
// ans[i][j] = combi i:not use j:num
int ans[2005][2005] = {0};

void solve();

int main() {
  int i;
  cin >> n >> m >> q;
  for(i = 0; i < n; ++i) cin >> a[i];
  solve();
  for(i = 0; i < q; ++i) {
    cin >> k >> x;
    cout << ans[k][m - x] << endl;
  }
  return 0;
}

void solve() {
  int i, j;
  for(i = 0; i <= n; ++i) dp[i][0] = 1;
  for(i = 1; i <= n; ++i)
    for(j = 1; j <= m; ++j) {
      dp[i][j] = dp[i][j - 1] + dp[i - 1][j];
      dp[i][j] %= N;
      if(j - a[i - 1] - 1 >= 0)
        dp[i][j] -= dp[i - 1][j - a[i - 1] - 1];
      while(dp[i][j] < 0) dp[i][j] += N;
      dp[i][j] %= N;
    }
  for(i = 1; i <= n; ++i) {
    for(j = 0; j <= m; ++j) {
      ans[i][j] = dp[n][j] % N;
      if(j != 0) ans[i][j] -= dp[n][j - 1];
      ans[i][j] %= N;
      if(j - a[i - 1] - 1 >= 0)
        ans[i][j] += ans[i][j - a[i - 1] - 1];
      while(dp[i][j] < 0) dp[i][j] += N;
      ans[i][j] %= N;
    }
  }
}

Submission Info

Judge Result