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POJ 2395 Out of Hay（MST）

【题目链接】http://poj.org/problem?id=2395
【解题思路】找最小生成树中权值最大的那条边输出，模板过的，出现了几个问题，开的数据不够大导致运行错误，第一次用模板，理解得不够深厚且模板有错误导致提交错误
 
 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cmath>
 5 #include<queue>
 6 #include<algorithm>
 7 #define INF 1000000002
 8 #define MAXN 2002
 9 #define SIZE 20200
10 
11 using namespace std;
12 
13 int eh[MAXN], tot, dist[MAXN];
14 bool visit[MAXN];
15 int n, m;
16 struct Edge{
17     int v, u, cost, next;
18     Edge(){}
19     Edge(int a, int b, int c, int d){
20         v = a, u = b, cost = c, next = d;
21     }
22     Edge(int a, int b){v = a, cost = b;}
23     bool operator < (const Edge &x) const{
24         return cost > x.cost;
25     }
26 };
27 struct Edge edge[SIZE];
28 
29 int prim(int s)
30 {
31     for(int i = 1; i <= n; ++i) visit[i] = false, dist[i] = INF;
32     dist[s] = 0;
33     priority_queue<Edge> que;
34     que.push(Edge(s, 0));
35     int ans = 0;
36     while(!que.empty())
37     {
38         Edge tmp = que.top();
39         que.pop();
40         int u = tmp.v, cost = tmp.cost;
41         if(visit[u]) continue;
42         if(cost > ans) ans = cost; 
43         visit[u] = true;
44         for(int i=eh[u]; i != -1; i = edge[i].next)
45         {
46             int v = edge[i].u;
47             if(!visit[v] && dist[v] > edge[i].cost)
48             {
49                 dist[v] = edge[i].cost;
50                 que.push(Edge(v, dist[v]));
51             }
52         }
53     }
54     return ans;
55 }
56 
57 void addedge(int a, int b, int c)
58 {
59     Edge e = Edge(a, b, c, eh[a]);
60     edge[tot] = e;
61     eh[a] = tot++;
62 }
63 
64 void init()
65 {
66     tot = 0;
67     memset(eh, -1, sizeof(eh));
68 }
69 
70 int main()
71 {
72     scanf("%d%d", &n, &m);
73     init();
74     for(int i = 1; i <= m; ++i)
75     {
76         int u, v, cost;
77         scanf("%d%d%d", &u, &v, &cost);
78         addedge(v, u, cost);
79         addedge(u, v, cost); 
80     }
81     printf("%d\n", prim(1));
82     return 0;
83 }

 

posted @ 2013-07-25 10:59  Gifur  阅读(351)  评论(0)  编辑  收藏  举报
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