OJ-Problems-Source/HDOJ/4276_autoAC.cpp
2016-09-04 15:25:29 +08:00

100 lines
2.4 KiB
C++

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
const int N=105;
int head[N],tot;
int dp[N][N*5];
struct Edge
{
int from,to,cost,pre;
Edge(){}
Edge(int a,int b,int c,int d){from=a;to=b;cost=c;pre=d;}
}edge[N*3];
void addEdge(int u,int v,int cost)
{
edge[tot]=Edge(u,v,cost,head[u]);
head[u]=tot++;
}
int spfa(int st,int ed)
{
queue<int> que;
int vis[N],dis[N],pre[N];
memset(vis,0,sizeof(vis));
memset(dis,0x7f,sizeof(dis));
memset(pre,-1,sizeof(pre));
que.push(st);
vis[st]=1; dis[st]=0;
while(!que.empty())
{
int u=que.front();
que.pop(); vis[u]=0;
for(int i=head[u];i!=-1;i=edge[i].pre)
{
int v=edge[i].to,cost=edge[i].cost;
if(dis[v]>dis[u]+cost)
{
dis[v]=dis[u]+cost;
pre[v]=i;
if(!vis[v])
{
vis[v]=1;
que.push(v);
}
}
}
}
for(int i=ed;i!=st;i=edge[pre[i]].from)
{
edge[pre[i]].cost=0;
edge[pre[i]^1].cost=0;
}
return dis[ed];
}
void dfs(int u,int fa,int coin)
{
for(int e=head[u];e!=-1;e=edge[e].pre)
{
int v=edge[e].to,cost=edge[e].cost*2;
if(v==fa||coin<cost) continue;
dfs(v,u,coin-cost);
for(int i=coin;i>=cost;i--)
{
for(int j=0;j+cost<=i;j++)
{
if(dp[u][i-j-cost]!=-1&&dp[v][j]!=-1)
dp[u][i]=max(dp[u][i],dp[u][i-j-cost]+dp[v][j]);
}
}
}
}
int main()
{
int n,t;
while(scanf("%d%d",&n,&t)!=EOF)
{
tot=0;
memset(dp,-1,sizeof(dp));
memset(head,-1,sizeof(head));
for(int i=0;i<n-1;i++)
{
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
addEdge(a,b,c);
addEdge(b,a,c);
}
for(int i=1;i<=n;i++) scanf("%d",&dp[i][0]);
t-=spfa(1,n);
if(t<0) puts("Human beings die in pursuit of wealth, and birds die in pursuit of food!");
else
{
dfs(1,0,t);
int res=0;
for(int i=0;i<=t;i++) res=max(res,dp[1][i]);
printf("%d\n",res);
}
}
return 0;
}