Submission #5340108

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Source Code Expand

#include <bits/stdc++.h>
#define REP(i, n) for(int i = 0; i < n; i++)
#define ALL(v) (v).begin(), (v).end()

using namespace std;
using ll = long long;

const int MOD = 1e9+7;

ll combination(int n, int r) {
  ll a[n+1][n+1];
  for (int i = 0; i <= n; ++i) {
    for (int j = 0; j <= i; ++j) {
      if (j == 0 or j == i) a[i][j] = 1;
      else a[i][j] = a[i-1][j-1]%MOD+a[i-1][j]%MOD;
    }
  }

  return a[n][r];
}

int main()
{
  int N, K; cin >> N >> K;

  if (N <= K) cout << combination(N, K%N) % MOD << endl;
  else cout << combination(N+K-1, K) % MOD << endl;
}

Submission Info

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