NYOJ 697 The Weight of Tree

题目链接：here~~

树形dp

#include <iostream>
#include <cstdio>
#include <string.h>
#include <vector>
using namespace std;
bool vis[100010];
int point[100010];
vector<int> m[100010];
int maxn;
int dfs(int i)
{
    vis[i]=1;
    int res=point[i], term, len=m[i].size();
    for (int j=0; j<len; j++)
    {
        if (vis[m[i][j]]==0)
        {
            term=dfs(m[i][j]);
            if (term>0) res+=term;//如果大于0，就加上，小于0不操作
        }
    }
    if (maxn<res) maxn=res;//更新最大值
    return res;
}
int main()
{
//	freopen("in", "r", stdin);
	int T, n, i, a, b;
	scanf("%d", &T);
	while (T--)
	{
	    memset(vis, 0, sizeof (vis));
	    scanf("%d", &n);
	    for (i=1; i<=n; i++)
	        scanf("%d", &point[i]);
	    for (i=1; i<n; i++)
	    {
	        scanf("%d%d", &a, &b);
	        m[a].push_back(b);
	        m[b].push_back(a);
	    }
	    maxn=1<<31;
	    dfs(1);
	    printf("%d\n", maxn);
	    for (i=1; i<=n; i++) m[i].clear();
	}
	return 0;
}