Contestants Division POJ - 3140 （简单树形dp）

#pragma comment(linker, "/STACK:1024000000,1024000000") //加栈
#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <queue>
#include <map>
#include <vector>
#include <set>
#include <string>
#include <math.h>
#include <stack>
using namespace std;
typedef long long ll;
const int maxn = 1e5+8;
#define inf 1e18+4
vector<int> g[maxn];
int n,m;
ll h[maxn];
ll dp[maxn];
ll ans2;
ll ans;
void dfs(int u,int pre)
{
    dp[u]=h[u];
    for(int i=0;i<g[u].size();i++)
    {
        int v=g[u][i];
        if(v==pre) continue;
        dfs(v,u);
        dp[u]+=dp[v];
    }
    //if(u!=1)
    //{
        ll M=0;
        if(ans-2*dp[u]>0)
        {
            M=ans-2*dp[u];
        }
        else
        {
            M=-(ans-2*dp[u]);
        }
        ans2=min(ans2,M);
   // }
}
int main(int argc, char const *argv[])
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif
    int Case=0;
    while(scanf("%d%d",&n,&m)!=EOF&&(n+m))
    {
        memset(dp,0,sizeof(dp));
        ans=0,ans2=inf;
        for(int i=1;i<=n;i++)
        {
            g[i].clear();
            scanf("%lld",&h[i]);
            ans+=h[i];
        }
        for(int i=1;i<=m;i++)
        {
            int u,v;
            scanf("%d%d",&u,&v);
            g[u].push_back(v);
            g[v].push_back(u);
        }
        dfs(1,0);
        printf("Case %d: %lld\n",++Case,ans2);
    }
    return 0;
}