Submission #44071

#TimeUsernameProblemLanguageResultExecution timeMemory
44071zadrgaAsceticism (JOI18_asceticism)C++14
4 / 100
23 ms2192 KiB
#include <bits/stdc++.h> using namespace std; #define pb push_back #define mp make_pair #define fi first #define se second #define INF (1LL << 55) #define MOD (1000 * 1000 * 1000 + 7) #define maxn 100111 typedef long long ll; typedef long double ld; typedef pair<int, int> pii; ll fakt[maxn], inv[maxn]; ll fastexp(ll x, ll y){ ll ret = 1LL; while(y){ if(y & 1) ret = (ret * x) % MOD; x = (x * x) % MOD; y >>= 1; } return ret; } ll C(ll x, ll y){ ll ret = fakt[x] * inv[y] % MOD * inv[x - y] % MOD; return ret; } ll eulerian_number(ll n, ll k){ ll ans = 0LL; for(int i = 0; i <= k + 1; i++){ ll cur = fastexp(-1LL, i) * C(n + 1LL, i) % MOD * fastexp(k + 1LL - i, n) % MOD; ans = (ans + cur) % MOD; } return ans; } void preprocess(){ fakt[0] = inv[0] = 1LL; for(ll i = 1; i < maxn; i++){ fakt[i] = (fakt[i - 1] * i) % MOD; inv[i] = fastexp(fakt[i], MOD - 2); } } int main(){ preprocess(); ll n, k; scanf("%lld%lld", &n, &k); printf("%lld\n", eulerian_number(n, n - k) ); return 0; }

Compilation message (stderr)

asceticism.cpp: In function 'int main()':
asceticism.cpp:57:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld", &n, &k);
  ~~~~~^~~~~~~~~~~~~~~~~~~~
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