Submission #1083905

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define fo(i,a,b) for(int i=(a);i<(b);i++)
#define MOD 1000000007
#define MP make_pair
#define PB push_back
typedef long long ll;

int N, K;
ll ans = 1;

ll inv (ll a) {
        ll e = MOD-2, r = 1ll;
        while (e) {
                if (e&1) r = r * a % MOD;
                e /= 2, a = a * a % MOD;
        }
        return r;
}

int main () {
        scanf("%d %d", &N, &K);

        ll x = (ll) N-K+1;

        if (K != 1) {


                ans = x % MOD;
                for (ll i = (ll) K; i < (ll) K + (K-2); i++) {
                        ans = ans * (x+i) % MOD;
                }
                for (ll i = 1ll; i < (ll) K; i++) ans = ans * inv(i) % MOD;

        }
        if (x > 2) {
                for (ll i = 0; i < x-2; i++) ans = ans * 2 % MOD;
        }


        printf("%lld\n", ans);

        return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:22:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &N, &K);
                               ^

Judge Result