Submission #373913

#	Time	Username	Problem	Language	Result	Execution time	Memory
373913		i_am_noob	Asceticism (JOI18_asceticism)	C++14	100 / 100	13 ms	2028 KiB

asceticism

#pragma GCC target("sse,sse2,sse3,ssse3,sse4,avx,avx2,avx512f")
#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops")
using namespace std;

#define ll long long
#define ull unsigned long long
#define ld long double
#define rep(a) rep1(i,a)
#define rep1(i,a) rep2(i,0,a)
#define rep2(i,b,a) for(int i=(b); i<((int)(a)); i++)
#define rep3(i,b,a) for(int i=(b); i>=((int)(a)); i--)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define pb push_back
#define inf 1010000000
//#define inf 4000000000000000000
#define eps 1e-9
#define sz(a) ((int)a.size())
#define pow2(x) (1ll<<(x))
#define ceiling(a,b) (((a)+(b)-1)/(b))
#ifdef i_am_noob
#define bug(...) cerr << "#" << __LINE__ << ' ' << #__VA_ARGS__ << "- ", _do(__VA_ARGS__)
template<typename T> void _do(T && x) {static int cnt=0;cerr << x << endl;cnt++;if(cnt>1000) exit(0);}
template<typename T, typename ...S> void _do(T && x, S&&...y) {cerr << x << ", "; _do(y...);}
#else
#define bug(...) 826
#endif

inline char readchar(){
    const int maxn=1000000;
    static char buf[maxn],*p=buf,*q=buf;
    if(p==q&&(q=(p=buf)+fread(buf,1,maxn,stdin))==buf) return EOF;
    else return *p++;
}
inline int readint(){
    int c=readchar(),x=0,neg=0;
    while((c<'0'||c>'9')&&c!='-'&&c!=EOF) c=readchar();
    if(c=='-') neg=1,c=readchar();
    while(c>='0'&&c<='9') x=(x<<3)+(x<<1)+(c^'0'),c=readchar();
    return neg?-x:x;
}

const int Mod=1000000007,Mod2=998244353;
const int MOD=Mod;
const int maxn=100005;
//i_am_noob
int n,k;
ll ans,fact[maxn],invf[maxn];

ll Pow(ll a, int b){
    ll res=1;
    while(b){
        if(b&1) res=res*a%MOD;
        a=a*a%MOD,b>>=1;
    }
    return res;
}

signed main(){
    ios_base::sync_with_stdio(0),cin.tie(0);
    #ifdef i_am_noob
    freopen("input1.txt","r",stdin);
    freopen("output1.txt","w",stdout);
    freopen("output2.txt","w",stderr);
    #endif
    fact[0]=1;
    rep2(i,1,maxn) fact[i]=fact[i-1]*i%MOD;
    invf[0]=invf[1]=1;
    rep2(i,2,maxn) invf[i]=invf[MOD%i]*(MOD-MOD/i)%MOD;
    rep2(i,2,maxn) invf[i]=invf[i-1]*invf[i]%MOD;
    cin >> n >> k;
    n--,k--;
    rep(k+1){
        ans+=Pow(k+1-i,n+1)*fact[n+2]%MOD*invf[i]%MOD*invf[n+2-i]%MOD*(i&1?-1:1);
        if(ans>=MOD) ans-=MOD;
        if(ans<0) ans+=MOD;
    }
    cout << ans << "\n";
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 51 / 51