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  • HDU 2242 考研路茫茫——空调教室

    考研路茫茫——空调教室

    http://acm.hdu.edu.cn/showproblem.php?pid=2242

    分析:

      树形dp,删边。

    代码:

     1 #include<cstdio>
     2 #include<algorithm>
     3 #include<cstring>
     4 
     5 using namespace std;
     6 
     7 const int MAXN = 10010;
     8 const int MAXM = 50010;
     9 
    10 struct Edge{
    11     int to,nxt;
    12 }e[MAXM];
    13 int head[MAXM],tot;
    14 int son[MAXN],Sum,ans;
    15 
    16 inline int read() {
    17     int x = 0,f = 1;char ch = getchar();
    18     for (; ch<'0'||ch>'9'; ch = getchar())
    19         if (ch=='-') f = -1;
    20     for (; ch>='0'&&ch<='9'; ch = getchar())
    21         x = x*10+ch-'0';
    22     return x*f;
    23 }
    24 inline void add_edge(int u,int v) {
    25     e[++tot].to = v,e[tot].nxt = head[u],head[u] = tot;
    26 }
    27 inline void init() {
    28     memset(head,0,sizeof(head));
    29     ans = 1e9; // ans也要初始化!!! 
    30     tot = Sum = 0;
    31 }
    32 void dfs(int u,int fa) {
    33     for (int i=head[u]; i; i=e[i].nxt) {
    34         int v = e[i].to;
    35         if (v==fa) continue;
    36         dfs(v,u);
    37         son[u] += son[v];
    38         ans = min(ans,abs(Sum-son[v]-son[v]));
    39     }
    40 }
    41 
    42 int main() { 
    43     int n,m,CASE = 0;
    44     while (scanf("%d%d",&n,&m)!=EOF) {
    45         init();
    46         for (int i=1; i<=n; ++i) son[i] = read(),Sum += son[i];
    47         for (int u,v,i=1; i<=m; ++i) {
    48             u = read(),v = read();
    49             add_edge(u,v),add_edge(v,u);
    50         }
    51         dfs(0,-1);
    52         printf("Case %d: %d
    ",++CASE,ans);
    53     }
    54     return 0;
    55 }
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  • 原文地址:https://www.cnblogs.com/mjtcn/p/9585083.html
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