Starry

发表于 更新于 分类于 本文字数： 1.7k 阅读时长 ≈ 6 分钟

以前写的，把垃圾代码丢上来 :)

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发表于 更新于 本文字数： 316 阅读时长 ≈ 1 分钟

快速幂被卡两个点

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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

const int mod=1e9+7;
ll n,m,c,ans;

int qpow(int a,int b){
	int ret=1;
	for(;b;b>>=1,a=1ll*a*a%mod)if(b&1)ret=1ll*ret*a%mod;
	return ret;
}
int inv(int x){return qpow(x,mod-2);}
int fact[(int)1e5+9],inv_fact[(int)1e5+9],qow[(int)2e5+9]={1};
int C(int n,int m){
	if(m>n||n<0||m<0)return 0;
	return 1ll*fact[n]*inv_fact[m]%mod*inv_fact[n-m]%mod;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    fact[0]=1;
    f(i,1,400)fact[i]=1ll*fact[i-1]*i%mod;
	inv_fact[400]=inv(fact[400]);
	for(int i=400-1;i>=0;i--)inv_fact[i]=1ll*inv_fact[i+1]*(i+1)%mod;

    cin>>n>>m>>c;

    for(int k=0;k<=c;++k){
        for(int i=1;i<=n*m;++i)qow[i]=qow[i-1]*(c-k+1)%mod;
        for(int i=0;i<=n;++i)for(int j=0;j<=m;++j)ans=(ans+((i+j+k)&1?-1ll:1ll)*C(n,i)*C(m,j)%mod*C(c,k)%mod*qow[(n-i)*(m-j)]%mod+mod)%mod;
    }
    cout<<ans;
    return 0;
}

发表于 更新于 分类于 本文字数： 317 阅读时长 ≈ 1 分钟

数组没开够竟然是TLE…

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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

ll n,ans;
const int mod=998244353;

int qpow(ll a,ll b){
	int ret=1;
	for(;b;b>>=1,a=1ll*a*a%mod)if(b&1)ret=1ll*ret*a%mod;
	return ret;
}
int inv(int x){return qpow(x,mod-2);}
int fact[(int)1e6+9],inv_fact[(int)1e6+9];
int C(int n,int m){
	if(m>n||n<0||m<0)return 0;
	return 1ll*fact[n]*inv_fact[m]%mod*inv_fact[n-m]%mod;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n;
    fact[0]=1;
    f(i,1,n)fact[i]=1ll*fact[i-1]*i%mod;
	inv_fact[n]=inv(fact[n]);
	for(int i=n-1;i>=0;i--)inv_fact[i]=1ll*inv_fact[i+1]*(i+1)%mod;
    
    ll invc=inv(3);
	for(int i=1;i<=n;++i){
		ans=(ans+(i&1?1ll:-1ll)*C(n,i)*qpow(invc,i*n)%mod*(qpow(1+mod-qpow(invc,n-i),n)-1)%mod+mod)%mod;
	}
	ans=1ll*qpow(3,n*n+1)*ans%mod;
	for(int i=1;i<=n;++i){
		ans=(ans+(i&1?2ll:-2ll)*C(n,i)*qpow(3,i)%mod*qpow(3ll,n*(n-i))%mod+mod)%mod;
	}
	cout<<ans;
    return 0;
}

发表于 更新于 本文字数： 308 阅读时长 ≈ 1 分钟 
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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;

const int mod=1e9+7;
ll n,m,a[(int)1e3+9],dp[(int)1e3+9],ans;

int ksm(int a,int b){
	int ret=1;
	for(;b;b>>=1,a=1ll*a*a%mod)if(b&1)ret=1ll*ret*a%mod;
	return ret;
}
int inv(int x){return ksm(x,mod-2);}
int fact[(int)1e5+9],inv_fact[(int)1e5+9];
int C(int n,int m){
	if(m>n||n<0||m<0)return 0;
	return 1ll*fact[n]*inv_fact[m]%mod*inv_fact[n-m]%mod;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    fact[0]=1;
    f(i,1,2e3)fact[i]=1ll*fact[i-1]*i%mod;
	inv_fact[2000]=inv(fact[2000]);
	for(int i=2000-1;i>=0;i--)inv_fact[i]=1ll*inv_fact[i+1]*(i+1)%mod;

    cin>>n>>m; 
    f(i,1,m)cin>>a[i];
    for(int i=0;i<=n;++i){
    	dp[i]=1;
    	for(int j=1;j<=m;++j){
    		dp[i]=dp[i]*C(a[j]+n-i-1,n-i-1)%mod;
    	}
    	dp[i]=dp[i]*C(n,i)%mod;
    }

    for(int i=0;i<=n;++i){
    	ans=((ans+(i&1?-1ll:1ll)*dp[i])%mod+mod)%mod;
    }
    cout<<ans;
    return 0;
}

发表于 更新于 本文字数： 378 阅读时长 ≈ 1 分钟

洛谷P4859

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#include <bits/stdc++.h>
/*
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/hash_policy.hpp>
*/
using namespace std;

const double eps = 1e-10;
const double pi = 3.1415926535897932384626433832795;
const double eln = 2.718281828459045235360287471352;

#define f(i, a, b) for (int i = a; i <= b; i++)
#define scan(x) scanf("%d", &x)
#define mp make_pair
#define pb push_back
#define lowbit(x) (x&(-x))

#define fi first
#define se second
#define SZ(x) int((x).size())
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define summ(a) (accumulate(all(a), 0ll))

typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef vector<int> vi;

using ll=long long;
const int mod=1e9+9,N=2e3+9;
ll n,k,a[(int)2e3+9],b[(int)2e3+9],dp[(int)2e3+9][(int)2e3+9];

int ksm(int a,int b){
	int ret=1;
	for(;b;b>>=1,a=1ll*a*a%mod)if(b&1)ret=1ll*ret*a%mod;
	return ret;
}
int inv(int x){return ksm(x,mod-2);}
ll fact[N],inv_fact[N];
ll C(int n,int m){
	if(m>n||n<0||m<0)return 0;
	return 1ll*fact[n]*inv_fact[m]%mod*inv_fact[n-m]%mod;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>n>>k;
    fact[0]=1;
    f(i,1,n)fact[i]=1ll*fact[i-1]*i%mod;
	inv_fact[n]=inv(fact[n]);
	for(int i=n-1;i>=0;i--)inv_fact[i]=1ll*inv_fact[i+1]*(i+1)%mod;

    f(i,1,n)cin>>a[i];
    f(i,1,n)cin>>b[i];
    if((k^n)&1){cout<<'0';return 0;}
    sort(a+1,a+1+n);
    sort(b+1,b+1+n);
    f(i,0,n)dp[i][0]=1;

    for(int i=1;i<=n;++i){
    	for(int j=1;j<=n;++j){
    		dp[i][j]=(dp[i-1][j]+dp[i-1][j-1]*(lower_bound(b+1,b+1+n,a[i])-(b+1)-(j-1))%mod)%mod;
    	}
    }

    k=(n+k)>>1;
    ll ans=0,res;
    for(int i=k;i<=n;++i){
    	if((i^k)&1)res=-1;
    	else res=1;
    	ans=(ans+res*C(i,k)*dp[n][i]%mod*fact[n-i]%mod+mod)%mod;
    }
    cout<<(ans%mod+mod)%mod;
    return 0;
}

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