Submission #700027

#	Time	Username	Problem	Language	Result	Execution time	Memory
700027		urosk	Asceticism (JOI18_asceticism)	C++14	100 / 100	58 ms	1116 KiB

asceticism

#define here cerr<<"===========================================\n"
#define dbg(x) cerr<<#x<<": "<<x<<endl;
#include "bits/stdc++.h"
//#include <ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
#define ld double
#define ll long long
#define llinf 100000000000000000LL // 10^17
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define sz(a) (ll)(a.size())
#define all(a) a.begin(),a.end()
#define ceri(a,l,r) {cerr<<#a<<": ";for(ll i_ = l;i_<=r;i_++) cerr<<a[i_]<< " ";cerr<<endl;}
#define cer(a) {cerr<<#a<<": ";for(ll x_ : a) cerr<<x_<< " ";cerr<<endl;}

#define daj_mi_malo_vremena ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);

using namespace std;
//using namespace __gnu_pbds;
#define mod 1000000007
ll add(ll x,ll y){
    x+=y;
    if(x<0){
        x%=mod;
        x+=mod;
    }else{
        if(x>=mod) x%=mod;
    }
    return x;
}
ll mul(ll a,ll b){
	ll ans = (a*b)%mod;
	if(ans<0) ans+=mod;
	return ans;
}
ll po(ll x,ll y){
    if(y==0) return 1LL;
    ll ans = po(x,y/2);
    ans= mul(ans,ans);
    if(y&1) ans = mul(ans,x);
    return ans;
}
ll inv(ll x){return po(x,mod-2);}
#define maxn 100005
ll fact[maxn];
ll ch(ll n,ll k){
    ll ans = fact[n];
    ans = mul(ans,inv(fact[k]));
    ans = mul(ans,inv(fact[n-k]));
    return ans;
}
ll n,k;
void tc(){
    fact[0] = 1;
    for(ll i = 1;i<maxn;i++) fact[i] = mul(fact[i-1],i);
    cin >> n >> k;
    k--;
    ll ans = 0;
    for(ll i = 0;i<=k;i++){
        ll cur = ch(n+1,i);
        cur = mul(cur,po(k-i+1,n));
        if(i&1) ans = add(ans,-cur);
        else ans = add(ans,cur);
    }
    cout<<ans<<endl;
}
int main(){
	daj_mi_malo_vremena
    int t; t = 1;
    while(t--){
        tc();
    }
	return 0;
}

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