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 |
---|---|---|---|---|---|---|---|---|---|
#213574 | #2715. 8.4t4 | jsxheng | 100 | 790ms | 138604kb | C++11 | 1.3kb | 2024-11-12 21:04:47 | 2024-11-12 23:45:13 |
answer
#include<bits/stdc++.h>
#define int long long
using namespace std;
namespace IO{
template<typename T> inline void read(T &x){
bool f=1;x=0;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=0;ch=getchar();}
while(ch>='0'&&ch<='9')x=(x<<1)+(x<<3)+(ch&15),ch=getchar();
x=f?x:-x;
}
template<typename T> inline void write(T x){
if(x<0) putchar('-'),x=-x;
if(x>9) write(x/10);
putchar(('0'+x%10));
}
template <typename T,typename ...Args> inline void read(T &x,Args &...args){read(x);read(args...);}
template<typename T> inline void write(T x,char c){write(x),putchar(c);}
}
using namespace IO;
const int N=5005,mod=1e9+7;
int n,f[N][N],siz[N],C[N][N];
vector<int>e[N];
void dfs(int u,int fa){
f[u][1]=1,siz[u]=1;
for(int v:e[u]){
if(v!=fa){
dfs(v,u);
for(int i=siz[u];i;--i){
for(int j=siz[v];j;j--)f[u][i+j]=(f[u][i+j]+f[u][i]*f[v][j]%mod*C[i+j-1][j])%mod;
f[u][i]=f[u][i]*f[v][0]%mod;
}
siz[u]+=siz[v];
}
}
for(int i=siz[u];~i;--i)f[u][i]=(f[u][i]+f[u][i+1])%mod;
}
signed main(){
read(n);
for(int i=1,u,v;i<n;++i){
read(u,v);
e[u].push_back(v),e[v].push_back(u);
}
for(int i=0;i<=n;++i){
C[i][0]=1;
for(int j=1;j<=i;++j)C[i][j]=(C[i-1][j-1]+C[i-1][j])%mod;
}
dfs(1,1);
write(f[1][0]);
return 0;
}
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: 1380kb
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: 1376kb
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: 2ms
memory: 2152kb
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: 2ms
memory: 2156kb
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: 2156kb
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: 6332kb
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: 0ms
memory: 6328kb
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: 261ms
memory: 138544kb
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: 261ms
memory: 138604kb
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: 264ms
memory: 138532kb
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'