POJ 3140 Contestants Division

题目链接

题意很扯，就是给一棵树，每个结点有个值，然后把图劈成两半，差值最小，反正各种扯。

2B错误，导致WA了多次，无向图，建图搞成了有向了....

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 #include <cmath>
 #include <algorithm>
 using namespace std;
 #define LL __int64
 struct node
 {
     int u,v,next;
 }edge[];
 LL p[];
 LL dp[];
 int first[];
 int o[];
 int t;
 LL ans,sum;
 void CL()
 {
     t = ;
     memset(first,-,sizeof(first));
     memset(dp,,sizeof(dp));
     memset(o,,sizeof(o));
 }
 void add(int u,int v)
 {
     edge[t].u = u;
     edge[t].v = v;
     edge[t].next = first[u];
     first[u] = t ++;
 }
 void dfs(int x)
 {
     int i;
     LL minz,res;
     if(o[x]) return ;
     o[x] = ;
     res = p[x];
     for(i = first[x];i != -;i = edge[i].next)
     {
         dfs(edge[i].v);
         res += dp[edge[i].v];
     }
     dp[x] = res;
     minz = (sum - res) - res;
     if(minz < ) minz = -minz;
     if(ans > minz)
     ans = minz;
 }
 int main()
 {
     int n,m,i,u,v,cas = ;
     while(scanf("%d%d",&n,&m)!=EOF)
     {
         if(!n && !m) break;
         sum = ;
         CL();
         for(i = ;i <= n;i ++)
         {
             scanf("%I64d",&p[i]);
             sum += p[i];
         }
         ans = sum;
         for(i = ;i < m;i ++)
         {
             scanf("%d%d",&u,&v);
             add(u,v);
             add(v,u);
         }
         for(i = ;i <= n;i ++)
         {
             if(!o[i])
             {
                 dfs(i);
             }
         }
         printf("Case %d: %I64d\n",cas++,ans);
     }
     return ;
 }