Kruskal HDOJ 1233 还是畅通工程

 

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\n", sum); 55  } 56 }