sgu143 分类： sgu 2015-03-11 22:11 38人阅读 评论(0) 收藏

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<cmath>
#include<iostream>
#include<algorithm>

const int MAXN = 16005, INF = (1<<30)-1;

int n , ans = -INF;

int w[MAXN] = {0},f[MAXN] = {0};

int head[MAXN] = {0};
int el = 0;

struct edgetype
{
int v,next;

void get(int u0,int v0)
{
v = v0;
next = head[u0];
head[u0] = el;
}

}mp[MAXN<<1];

void dfs(int u, int fa)
{
int v;

f[u] = w[u];

for(int i = head[u]; i ; i = mp[i].next)
if((v = mp[i].v) != fa) dfs(v , u);

for(int i = head[u]; i ; i = mp[i].next)
if((v = mp[i].v) != fa)
if(f[v] > 0) f[u] += f[v];
}

int main()
{
#ifndef ONLINE_JUDGE
freopen("sgu143.in","r",stdin);
freopen("sgu143.out","w",stdout);
#endif

scanf("%d",&n);

for(int i = 1; i <= n;i++)
scanf("%d",&w[i]);
for(int i = 1; i < n;i++)
{
int u,v;
scanf("%d%d",&u,&v);

mp[++el].get(u,v);
mp[++el].get(v,u);
}

dfs(1 ,false);

for(int i = 1; i <= n;i++)
ans = std::max(ans , f[i]);

printf("%d\n",ans);

#ifndef ONLINE_JUDGE
fclose(stdin);
fclose(stdout);
#endif
}