POJ-1287 Networking---裸的不能再裸的MST

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<cmath>
 6 #include<queue>
 7 #include<stack>
 8 #include<map>
 9 #include<sstream>
10 using namespace std;
11 typedef long long ll;
12 const int maxn = 3e5 + 10;
13 const int INF = 1 << 30;
14 int dir[4][2] = {1,0,0,1,-1,0,0,-1};
15 int T, n, m, x;
16 struct edge
17 {
18     int u, v, w;
19     bool operator <(const edge& a)const
20     {
21         return w < a.w;
22     }
23 };
24 edge a[maxn];
25 int par[600], high[600];
26 //初始化n个元素
27 void init(int n)
28 {
29     for(int i = 0; i < n; i++)
30     {
31         par[i] = i;
32         high[i] = 0;
33     }
34 }
35 //查询树的根
36 int Find(int x)
37 {
38     return par[x] == x ? x : par[x] = Find(par[x]);//路径压缩
39 }
40 void unite(int x, int y)
41 {
42     x = Find(x);
43     y = Find(y);
44     if(x == y)return;
45     if(high[x] < high[y])par[x] = y;//y的高度高，将x的父节点设置成y
46     else
47     {
48         par[y] = x;
49         if(high[x] == high[y])high[x]++;
50     }
51 }
52 bool same(int x, int y)
53 {
54     return Find(x) == Find(y);
55 }
56 void kruskal(int n, int m)//点数n，边数m
57 {
58     int sum_mst = 0;//mst权值
59     int num= 0;//已经选择的边的边数
60     sort(a, a + m);//边进行排序
61     init(n);//初始化并查集
62     for(int i = 0; i < m; i++)
63     {
64         int u = a[i].u;
65         int v = a[i].v;
66         if(Find(u - 1) != Find(v - 1))//图最开始的下标是1，并查集是0
67         {
68             //printf("%d %d %d\n", u, v, a[i].w);
69             sum_mst += a[i].w;
70             num++;
71             unite(u - 1, v - 1);
72         }
73         if(num >= n - 1)break;
74     }
75     //printf("weight of mst is %d\n", sum_mst);
76     cout<<sum_mst<<endl;
77 }
78 int main()
79 {
80     while(cin >> n && n)
81     {
82         cin >> m;
83         for(int i = 0; i < m; i++)
84         {
85             cin >> a[i].u >> a[i].v >> a[i].w;
86         }
87         kruskal(n, m);
88     }
89     return 0;
90 }