hdu 1162 Eddy's picture(最小生成树Kruskal)

/*Author: ACb0yDate: 2010年9月16日1:06:03Type: MST KruskalProblemId: hdu 1162 Eddy's pictureResult: 2960095 2010-09-16 01:04:47 Accepted 1162 15MS 480K 1267 B G++ ACb0y */#include <iostream>#include <cmath>using namespace std;struct Point {double x;double y;};struct edge {int x;int y;double w;};int n;int g[110][110];int father[110];Point points[110];edge edges[10100];double get_dis(int a, int b) {return sqrt((points[a].x - points[b].x) * (points[a].x - points[b].x) + (points[a].y - points[b].y) * (points[a].y - points[b].y));}int cmp(const void * a, const void * b) {edge * pa = (edge *) a;edge * pb = (edge *) b;return pa->w > pb->w ? 1 : -1;}int find(int x) {if (x != father[x]) {return find(father[x]);}return x;}int main(){int i, j;#ifndef ONLINE_JUDGEfreopen("1162.txt", "r", stdin);#endifwhile (cin >> n) {for (i = 1; i <= n; i++) {scanf("%lf%lf", &points[i].x, &points[i].y); }int c = 0;for (i = 1; i <= n; i++) {for (j = 1; j <= n; j++) {edges[c].w = get_dis(i, j);edges[c].x = i;edges[c].y = j;c++;}}qsort(edges, c, sizeof(edge), cmp);for (i = 1; i <= n; i++) {father[i] = i;}double ans = 0;for (i = 0; i < c; i++) {int x = find(edges[i].x);int y = find(edges[i].y);if (x != y) {ans += edges[i].w;father[x] = y;}}printf("%.2lf/n", ans);}return 0;}