poj 1192最优连通子集（简单树形dp）

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;

const int maxn = 1005;
const int INF = 0x3f3f3f;

int dp[maxn];
vector<int> G[maxn];
int W[maxn];
int N;
struct Point{
int x,y;
}P[maxn];
int ans;

void dfs(int u,int fa){
dp[u] = W[u];
for(int i=0;i<G[u].size();i++){
int v = G[u][i];
if(v == fa) continue;
dfs(v,u);
dp[u] += max(dp[v],0);
}
ans = max(ans,dp[u]);
}

int main()
{
// freopen("E:\\acm\\input.txt","r",stdin);
scanf("%d",&N);
for(int i=1;i<=N;i++){
scanf("%d %d",&P[i].x,&P[i].y);
scanf("%d",&W[i]);
}
for(int i=1;i<=N;i++)
for(int j=i+1;j<=N;j++)
if(abs(P[i].x-P[j].x) + abs(P[i].y-P[j].y) == 1){
G[i].push_back(j);
G[j].push_back(i);
}

ans = -INF;
dfs(1,-1);
printf("%d\n",ans);
}