mirror of
https://github.com/Kiritow/OJ-Problems-Source.git
synced 2024-03-22 13:11:29 +08:00
87 lines
2.2 KiB
C++
87 lines
2.2 KiB
C++
#include <stdio.h>
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#include <string.h>
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#include <vector>
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#include <algorithm>
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#define N 70
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#define S 600
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using namespace std;
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int n,l,s,vis[N],fa[N];
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vector<int>gra[N];
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double dp[N][S];
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void dfs(int d,int p)
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{
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vis[d]=1;fa[d]=p;
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int len=gra[d].size();
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if(p!=-1&&len==1)
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{
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dp[d][0]=1;
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for(int i=1;i<=s;i++)dp[d][i]=0;
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return ;
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}
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for(int i=0;i<len;i++)
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if(!vis[gra[d][i]])dfs(gra[d][i],d);
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double sum[S]={0};
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for(int i=0;i<=s;i++)
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{
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if(i*2<=s)
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{
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dp[d][i]=1;
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for(int j=0;j<len;j++)
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{
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int e=gra[d][j];
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if(fa[e]!=d)continue;
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double tmp=0;
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for(int k=0;k<=min(l,i);k++)
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for(int h=0;h<=i-k;h++)
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tmp+=dp[e][h];
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tmp/=(l+1);
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dp[d][i]*=tmp;
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}
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if(i>0)dp[d][i]-=sum[i-1],sum[i]=dp[d][i]+sum[i-1];
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else sum[i]=dp[d][i];
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}
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else
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{
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int op=s-i;
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dp[d][i]=0;
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for(int j=0;j<len;j++)
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{
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int e=gra[d][j];
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if(fa[e]!=d)continue;
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double tmp1=0;
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for(int k=0;k<=min(l,op);k++)
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for(int h=0;h<=op-k;h++)
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tmp1+=dp[e][h];
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tmp1/=(l+1);
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double tmp2=0;
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for(int k=0;k<=min(l,i);k++)
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tmp2+=dp[e][i-k];
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tmp2/=(l+1);
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dp[d][i]+=sum[op]*tmp2/tmp1;
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}
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}
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}
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}
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int main()
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{
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int ncase;
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scanf("%d",&ncase);
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for(int u=1;u<=ncase;u++)
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{
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scanf("%d%d%d",&n,&l,&s);
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for(int i=1;i<=n;i++)gra[i].clear();
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for(int i=1;i<n;i++)
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{
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int a,b;
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scanf("%d%d",&a,&b);
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gra[a].push_back(b);
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gra[b].push_back(a);
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}
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memset(vis,0,sizeof(vis));
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dfs(1,-1);
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double ans=0;
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for(int i=0;i<=s;i++)ans+=dp[1][i];
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printf("Case %d: %.6lf\n",u,ans);
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}
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}
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