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. 8.4t4 | nullptr_qwq | 100 | 393ms | 21720kb | C++11 | 6.2kb | 2024-11-12 18:51:07 | 2024-11-12 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'