Submission #2199492

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Source Code Expand

#include <cstdio>

using namespace std;

#define REP(i,n)   for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for(int i=(b); i<=(int)(e); i++)

typedef long long ll;

//------------------------------------------------------------------------------
ll mod_pow(ll x, ll n, ll mod) {
  ll res = 1;
  while (n > 0) {
    if (n & 1) {
      res = res * x % mod;
    }
    x = x * x % mod;
    n >>= 1;
  }
  return res;
}

ll mod_inverse(ll x, ll mod) {
  return mod_pow(x, mod - 2, mod);
}

ll mod_comb2(ll n, ll k, ll mod) {
  if (n < 0 || k < 0 || n < k) return 0;
  if (k > n - k) k = n - k;
  if (k == 0) return 1;
  ll a = 1, b = 1;
  while(k > 0) {
    a = a * n-- % mod;
    b = b * k-- % mod;
  }
  return a * mod_inverse(b, mod) % mod;
}

//------------------------------------------------------------------------------
const int MOD = 1e9+7;

int N, K;

void solve() {
  int ans = 0;
  if (N > K) {
    ans = mod_comb2(N + K -1, K, MOD);
  } else {
    ans = mod_comb2(N, K % N, MOD);
  }
  printf("%d\n", ans);
}

void input() {
  scanf("%d%d", &N, &K);
}

int main() {
  input();
  solve();
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘void input()’:
./Main.cpp:55:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &N, &K);
                        ^

Judge Result