题目传送门
1 /*
2 最小生成树之kruskal算法--并查集（数据结构）实现
3 建立一个结构体，记录两点和它们的距离，依照距离升序排序
4 不连通就累加距离，即为最小生成树的长度
5 */
6 #include <cstdio>
7 #include <algorithm>
8 #include <cstring>
9 #include <cmath>
10 using namespace std;
11
12 const int MAXN = 5e3 + 10;
13 const int INF = 0x3f3f3f3f;
14 int rt[MAXN];
15 struct Node
16 {
17 int u, v, w;
18 }node[MAXN];
19
20 bool cmp(Node x, Node y) {return x.w < y.w;}
21
22 int Find(int x) {return (rt[x] == -1) ? x : rt[x] = Find (rt[x]);}
23
24 void Union(int x, int y)
25 {
26 x = Find (x); y = Find (y);
27 if (x > y) rt[y] = x;
28 else if (x < y) rt[x] = y;
29 }
30
31 bool same(int x, int y) {return (Find (x) == Find (y));}
32
33 int main(void) //HDOJ 1233 还是畅通工程
34 {
35 //freopen ("inB.txt", "r", stdin);
36 int n, m;
37
38 while (~scanf ("%d", &n) && n)
39 {
40 m = n * (n - 1) / 2;
41 memset (rt, -1, sizeof (rt));
42 for (int i=1; i<=m; ++i)
43 {
44 scanf ("%d%d%d", &node[i].u, &node[i].v, &node[i].w);
45 }
46 sort (node+1, node+1+m, cmp);
47 int sum = 0;
48 for (int i=1; i<=m; ++i)
49 {
50 int x = node[i].u; int y = node[i].v;
51 int w = node[i].w;
52 if (!same (x, y)) {Union (x, y); sum += w;}
53 }
54 printf ("%d
", sum);
55 }
56 }