POJ 1192-optimal connected subset tree DP

#include<iostream>#include<stack>#include<queue>#include<stdio.h>#include<algorithm>#include<string.h>#include<cmath>#define ll long long#define oo 1000000007#define MAXN 1005using namespace std;struct node{      int x,y,c;}point[MAXN];int dp[MAXN],t;vector<int> line[MAXN];bool used[MAXN];void dfs(int x){      int i,m=line[x].size();      vector<int> h;      dp[x]=0;      h.clear();      for (i=0;i<m;i++)        if (!used[line[x][i]])        {             used[line[x][i]]=true;             h.push_back(line[x][i]);        }      m=h.size();      for (i=0;i<m;i++)      {            dfs(h[i]);            if (dp[h[i]]>=0) dp[x]+=dp[h[i]];      }      dp[x]+=point[x].c;      t=max(t,dp[x]);      return;}int main(){      int i,j,n,ans;       while (~scanf("%d",&n))      {            for (i=1;i<=n;i++)            {                  scanf("%d%d%d",&point[i].x,&point[i].y,&point[i].c);                  line[i].clear();            }            for (i=1;i<=n;i++)               for (j=1;j<=n;j++)                  if (abs(point[i].x-point[j].x)+abs(point[i].y-point[j].y)==1)                    line[i].push_back(j);            memset(used,false,sizeof(used));            ans=-oo;            for (i=1;i<=n;i++)              if (!used[i])              {                    t=-oo;                    used[i]=true;                    dfs(i);                    ans=max(t,ans);              }            printf("%d\n",ans);      }      return 0;}