hdu 1520 树状 dp

题意 给出一棵树 每个节点有权值  要求父节点和子节点不能同时取 求能够取得的最大值简单的树状dp，却RE了两次，WA了一次....无语，直接上代码：#include<iostream>#include<cstdio>#include<algorithm>#include<memory.h>using namespace std;const int INF=6002;int n,dp[INF][2],NE,node[INF],root[INF];int head[INF],vis[INF];struct nod{    int u,v,val,next;} Edge[INF*2];void addEdge(int u,int v,int val){    Edge[NE].u=u;    Edge[NE].v=v;    Edge[NE].val=val;    Edge[NE].next=head[u];    head[u]=NE++;}void dfs(int u,int fa){    int i,j;    for(i=head[u]; i!=-1; i=Edge[i].next)    {        int r=Edge[i].v;        if(r==fa) continue;        if(vis[r]==1) continue;        dfs(r,u);        dp[u][0]+=max(0,max(dp[r][0],dp[r][1]));        dp[u][1]+=(dp[r][0]>0?dp[r][0]:0);        vis[r]=1;    }}int main(){    int i,j,l,k;    while(scanf("%d",&n)!=EOF)    {        int ans=0;         NE=0;        memset(vis,0,sizeof(vis));        memset(head,-1,sizeof(head));        memset(root,0,sizeof(root));        memset(dp,0,sizeof(dp));        for(i=1; i<=n; i++) cin>>node[i],dp[i][1]=node[i];        while(scanf("%d%d",&l,&k),(l||k))        {            addEdge(k,l,node[k]);           // addEdge(l,k,node[l]);            root[k]=1;            //root[l]=1;        }        for(i=1; i<=n; i++)        {            if(root[i])            {                dfs(i,0);                ans=max(ans,max(dp[i][1],dp[i][0]));            }        }        cout<<ans<<endl;    }    return 0;}