UVa 1208 - Oreon

題目：給你一些圖，輸出圖的最小生成樹上的邊（包括頂點）。

分析：圖論，最小生成樹，并查集。利用kruskal算法求解即可。

說明：╮(╯▽╰)╭。

#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <cstdio>

using namespace std;

typedef struct _enode
{
	int point1;
	int point2;
	int weight;
}enode;
enode E[10001];

//union_set
int sets[101];
int rank[101];

void set_inital(int a, int b)
{
	for ( int i = a; i <= b; ++ i) {
		rank[i] = 0;
		sets[i] = i;
	}
}

int  set_find(int a)
{
	if (a != sets[a])
		sets[a] = set_find(sets[a]);
	return sets[a];
}

void set_union(int a, int b)
{
	if (rank[a] < rank[b])
		sets[a] = b;
	else {
		if (rank[a] == rank[b])
			rank[a] ++;
		sets[b] = a;
	}
}
//end_union_set

int cmp_e(enode a, enode b)
{
	if (a.weight == b.weight) {
		if (a.point1 == b.point1)
			return a.point2 < b.point2;
		else return a.point1 < b.point1;
	}else return a.weight < b.weight;
}

int kruskal(int n, int m)
{
	sort(E, E+m, cmp_e);
	set_inital(0, n);
	for (int i = 0; i < m; ++ i) {
		int A = set_find(E[i].point1);
		int B = set_find(E[i].point2);
		if (A != B) { 
			set_union(A, B);
			printf("%c-%c %d\n",E[i].point1+'A',E[i].point2+'A',E[i].weight);
		}
	}
}

int main()
{
	int t, n, a, c;
	while (~scanf("%d",&t))
	for (int k = 1; k <= t; ++ k) {
		scanf("%d",&n);
		int e_count = 0;
		for (int i = 0; i < n; ++ i)
		for (int j = 0; j < n; ++ j) {
			scanf("%d%c",&a,&c);
			E[e_count].point1 = i<j?i:j;
			E[e_count].point2 = j>i?j:i;
			E[e_count].weight = a;
			if (a) e_count ++;
		}
		
		printf("Case %d:\n",k);
		kruskal(n, e_count);
	}
	
	return 0;
}