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ID题目提交者结果用时内存语言文件大小提交时间测评时间
#213506#2715. 8.4t4nullptr_qwq100393ms21720kbC++116.2kb2024-11-12 18:51:072024-11-12 23:06:45

answer

// QOJ5357
// 做过,太不幸了。


// 私は猫です

#include<bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define pb push_back
#define mkp make_pair
#define fi first
#define se second
#define inf 1000000000
#define infll 1000000000000000000ll
#define pii pair<int,int>
#define rep(i,a,b,c) for(int i=(a);i<=(b);i+=(c))
#define per(i,a,b,c) for(int i=(a);i>=(b);i-=(c))
#define F(i,a,b) for(int i=a,i##end=b;i<=i##end;i++)
#define dF(i,a,b) for(int i=a,i##end=b;i>=i##end;i--)
#define cmh(sjy) while(sjy--)
#define lowbit(x) (x&(-x))
#define HH printf("\n")
#define eb emplace_back
#define poly vector<int>
#define SZ(x) ((int)x.size())
using namespace std;
ll read(){
	ll x=0,f=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-') f=-1;c=getchar();}
	while(c>='0'&&c<='9') x=(x<<3)+(x<<1)+(c^48),c=getchar();
	return x*f;
}
namespace Fastio{struct Reader{template<typename T>Reader&operator>>(T&x){x=0;short f=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-')f*=-1;c=getchar();}while(c>='0'&&c<='9')x=(x<<3)+(x<<1)+(c^48),c=getchar();x*=f;return*this;}Reader&operator>>(double&x){x=0;double t=0;short f=1,s=0;char c=getchar();while((c<'0'||c>'9')&&c!='.'){if(c=='-')f*=-1;c=getchar();}while(c>='0'&&c<='9'&&c!='.')x=x*10+(c^48),c=getchar();if(c=='.')c=getchar();else{x*=f;return*this;}while(c>='0'&&c<='9')t=t*10+(c^48),s++,c=getchar();while(s--)t/=10.0;x=(x+t)*f;return*this;}Reader&operator>>(long double&x){x=0;long double t=0;short f=1,s=0;char c=getchar();while((c<'0'||c>'9')&&c!='.'){if(c=='-')f*=-1;c=getchar();}while(c>='0'&&c<='9'&&c!='.')x=x*10+(c^48),c=getchar();if(c=='.')c=getchar();else{x*=f;return*this;}while(c>='0'&&c<='9')t=t*10+(c^48),s++,c=getchar();while(s--)t/=10.0;x=(x+t)*f;return*this;}Reader&operator>>(__float128&x){x=0;__float128 t=0;short f=1,s=0;char c=getchar();while((c<'0'||c>'9')&&c!='.'){if(c=='-')f*=-1;c=getchar();}while(c>='0'&&c<='9'&&c!='.')x=x*10+(c^48),c=getchar();if(c=='.')c=getchar();else{x*=f;return*this;}while(c>='0'&&c<='9')t=t*10+(c^48),s++,c=getchar();while(s--)t/=10.0;x=(x+t)*f;return*this;}Reader&operator>>(char&c){c=getchar();while(c==' '||c=='\n'||c=='\r')c=getchar();return*this;}Reader&operator>>(char*str){int len=0;char c=getchar();while(c==' '||c=='\n'||c=='\r')c=getchar();while(c!=' '&&c!='\n'&&c!='\r')str[len++]=c,c=getchar();str[len]='\0';return*this;}Reader&operator>>(string&str){str.clear();char c=getchar();while(c==' '||c=='\n'||c=='\r')c=getchar();while(c!=' '&&c!='\n'&&c!='\r')str.push_back(c),c=getchar();return*this;}Reader(){}}cin;const char endl='\n';struct Writer{const int Setprecision=6;typedef int mxdouble;template<typename T>Writer&operator<<(T x){if(x==0){putchar('0');return*this;}if(x<0)putchar('-'),x=-x;static short sta[40];short top=0;while(x>0)sta[++top]=x%10,x/=10;while(top>0)putchar(sta[top]+'0'),top--;return*this;}Writer&operator<<(double x){if(x<0)putchar('-'),x=-x;mxdouble _=x;x-=(double)_;static short sta[40];short top=0;while(_>0)sta[++top]=_%10,_/=10;if(top==0)putchar('0');while(top>0)putchar(sta[top]+'0'),top--;putchar('.');for(int i=0;i<Setprecision;i++)x*=10;_=x;while(_>0)sta[++top]=_%10,_/=10;for(int i=0;i<Setprecision-top;i++)putchar('0');while(top>0)putchar(sta[top]+'0'),top--;return*this;}Writer&operator<<(long double x){if(x<0)putchar('-'),x=-x;mxdouble _=x;x-=(long double)_;static short sta[40];short top=0;while(_>0)sta[++top]=_%10,_/=10;if(top==0)putchar('0');while(top>0)putchar(sta[top]+'0'),top--;putchar('.');for(int i=0;i<Setprecision;i++)x*=10;_=x;while(_>0)sta[++top]=_%10,_/=10;for(int i=0;i<Setprecision-top;i++)putchar('0');while(top>0)putchar(sta[top]+'0'),top--;return*this;}Writer&operator<<(__float128 x){if(x<0)putchar('-'),x=-x;mxdouble _=x;x-=(__float128)_;static short sta[40];short top=0;while(_>0)sta[++top]=_%10,_/=10;if(top==0)putchar('0');while(top>0)putchar(sta[top]+'0'),top--;putchar('.');for(int i=0;i<Setprecision;i++)x*=10;_=x;while(_>0)sta[++top]=_%10,_/=10;for(int i=0;i<Setprecision-top;i++)putchar('0');while(top>0)putchar(sta[top]+'0'),top--;return*this;}Writer&operator<<(char c){putchar(c);return*this;}Writer&operator<<(char*str){int cur=0;while(str[cur])putchar(str[cur++]);return*this;}Writer&operator<<(const char*str){int cur=0;while(str[cur])putchar(str[cur++]);return*this;}Writer&operator<<(string str){int st=0,ed=str.size();while(st<ed)putchar(str[st++]);return*this;}Writer(){}}cout;}using namespace Fastio;
#define cin Fastio::cin
#define cout Fastio::cout
#define endl Fastio::endl
template<typename T>inline void chkmax(T &x,const T &y){ x=std::max(x,y); }
template<typename T>inline void chkmin(T &x,const T &y){ x=std::min(x,y); }
const int mod=1e9+7,maxn=5005;
inline int qpow(int x,ll y){
	int rt=1;
	for(;y;y>>=1,x=1ll*x*x%mod) if(y&1) rt=1ll*rt*x%mod;
	return rt;
}
inline void inc(int &x,const int y){ x=(x+y>=mod)?(x+y-mod):(x+y); }
inline void dec(int &x,const int y){ x=(x>=y)?(x-y):(x+mod-y); }
inline void mul(int &x,const int y){ x=1ll*x*y%mod; }
inline int add(const int x,const int y){ return (x+y>=mod)?(x+y-mod):(x+y); }
inline int sub(const int x,const int y){ return (x>=y)?(x-y):(x+mod-y); }
inline int prod(const int x,const int y){ return 1ll*x*y%mod; }
namespace combi{
	int fac[maxn],ifac[maxn],inv[maxn];
	void init(const int N){
		fac[0]=ifac[0]=inv[0]=1;
		F(i,1,N)fac[i]=1ll*fac[i-1]*i%mod;
		ifac[N]=qpow(fac[N],mod-2);
		dF(i,N-1,1)ifac[i]=1ll*ifac[i+1]*(i+1)%mod;
		F(i,1,N)inv[i]=1ll*ifac[i]*fac[i-1]%mod;
	}
	inline int C(const int n,const int m){
		if(m>n||n<0||m<0) return 0;
		return 1ll*fac[n]*ifac[m]%mod*ifac[n-m]%mod;
	}
}
using namespace combi;
vector<int>g[maxn];
int siz[maxn],n,f[maxn][maxn],pre[maxn],nxt[maxn];
void dfs(int u,int fa=0){
	f[u][1]=siz[u]=1;
	for(auto v:g[u])if(v^fa){
		dfs(v,u);
		F(i,1,siz[v])pre[i]=add(pre[i-1],f[v][i]);
		F(i,1,siz[u]+siz[v])nxt[i]=0;
		F(i,1,siz[u])F(j,0,siz[v])inc(nxt[i+j],1ll*f[u][i]*sub(pre[siz[v]],pre[max(0,j-1)])%mod*C(i+j-1,i-1)%mod);
		F(i,1,siz[u]+siz[v])f[u][i]=nxt[i];
		siz[u]+=siz[v];
	}
}
void solve(){
	cin>>n,init(n);
	F(i,1,n-1){
		int u,v; cin>>u>>v;
		g[u].push_back(v),g[v].push_back(u);
	} dfs(1);
	int ans=0;
	F(i,1,n)inc(ans,f[1][i]);
	cout<<ans;
}
signed main(){
	// ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int zsy=1;
	F(____,1,zsy)solve();
}

详细

小提示:点击横条可展开更详细的信息

Test #1:

score: 10
Accepted
time: 0ms
memory: 1356kb

input:

10
1 2
1 3
3 4
3 5
3 6
3 7
1 8
5 9
5 10

output:

227506

result:

ok found '227506.00000', expected '227506.00000', error '0.00000'

Test #2:

score: 10
Accepted
time: 0ms
memory: 1352kb

input:

10
1 2
1 3
3 4
4 5
5 6
4 7
5 8
8 9
8 10

output:

70140

result:

ok found '70140.00000', expected '70140.00000', error '0.00000'

Test #3:

score: 10
Accepted
time: 0ms
memory: 1720kb

input:

100
1 2
1 3
1 4
3 5
5 6
4 7
7 8
8 9
8 10
3 11
7 12
1 13
5 14
8 15
10 16
7 17
1 18
6 19
10 20
15 21
7...

output:

875072841

result:

ok found '875072841.00000', expected '875072841.00000', error '0.00000'

Test #4:

score: 10
Accepted
time: 0ms
memory: 1724kb

input:

100
1 2
2 3
3 4
4 5
4 6
6 7
5 8
8 9
8 10
1 11
6 12
4 13
9 14
13 15
7 16
3 17
15 18
17 19
9 20
8 21
4...

output:

706867541

result:

ok found '706867541.00000', expected '706867541.00000', error '0.00000'

Test #5:

score: 10
Accepted
time: 0ms
memory: 1728kb

input:

100
1 2
2 3
3 4
2 5
2 6
5 7
2 8
4 9
7 10
5 11
11 12
6 13
8 14
13 15
5 16
11 17
16 18
11 19
7 20
19 2...

output:

515055734

result:

ok found '515055734.00000', expected '515055734.00000', error '0.00000'

Test #6:

score: 10
Accepted
time: 0ms
memory: 3364kb

input:

500
1 2
1 3
3 4
3 5
5 6
1 7
3 8
8 9
4 10
6 11
7 12
2 13
11 14
8 15
7 16
9 17
2 18
3 19
15 20
2 21
20...

output:

28964814

result:

ok found '28964814.00000', expected '28964814.00000', error '0.00000'

Test #7:

score: 10
Accepted
time: 3ms
memory: 3364kb

input:

500
1 2
1 3
1 4
2 5
5 6
5 7
4 8
8 9
1 10
4 11
8 12
6 13
13 14
13 15
12 16
1 17
10 18
13 19
1 20
1 21...

output:

900482908

result:

ok found '900482908.00000', expected '900482908.00000', error '0.00000'

Test #8:

score: 10
Accepted
time: 126ms
memory: 21700kb

input:

5000
1 2
1 3
1 4
3 5
3 6
5 7
4 8
4 9
1 10
5 11
6 12
10 13
12 14
14 15
12 16
8 17
14 18
9 19
8 20
20 ...

output:

255910011

result:

ok found '255910011.00000', expected '255910011.00000', error '0.00000'

Test #9:

score: 10
Accepted
time: 129ms
memory: 21720kb

input:

5000
1 2
1 3
1 4
2 5
1 6
5 7
2 8
5 9
4 10
9 11
10 12
8 13
7 14
13 15
12 16
5 17
9 18
8 19
3 20
4 21
...

output:

506490313

result:

ok found '506490313.00000', expected '506490313.00000', error '0.00000'

Test #10:

score: 10
Accepted
time: 135ms
memory: 21696kb

input:

5000
1 2
1 3
1 4
4 5
4 6
3 7
2 8
8 9
6 10
9 11
3 12
3 13
7 14
13 15
4 16
10 17
9 18
10 19
5 20
17 21...

output:

738067707

result:

ok found '738067707.00000', expected '738067707.00000', error '0.00000'