克鲁斯卡尔Kruskal

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#define MAX 100

/* 定义边(x,y)，权为w */
typedef struct
{
int x, y;
int w;
}edge;

edge e[MAX];
/* rank[x]表示x的秩 */
int rank[MAX];
/* father[x]表示x的父节点 */
int father[MAX];
int sum;
//typedef int (*cmptr)(const int a, const int b);
int cmp(const void*a,const void*b)
{
return (*(edge*)a).w>(*(edge*)b).w?1:-1;
}
/*堆排序*/

/* 初始化集合 */
void Make_Set(int x)
{
father[x] = x;
rank[x] = 0;
}

/* 查找x元素所在的集合,回溯时压缩路径 */
int Find_Set(int x)
{
if (x != father[x])
{
father[x] = Find_Set(father[x]);
}
return father[x];
}

/* 合并x,y所在的集合 */
void Union(int x, int y, int w)
{

if (x == y) return;
/* 将秩较小的树连接到秩较大的树后 */
if (rank[x] > rank[y])
{
father[y] = x;
}
else
{
if (rank[x] == rank[y])
{
rank[y]++;
}
father[x] = y;
}
sum += w;
}

/* 主函数 */
int main()
{

int i, n;
int x, y;
char chx, chy;
for(i=1;i<=26;i++)
Make_Set(i);

scanf("%d", &n);
getchar();

for (i = 1; i <=n; i++)
{
scanf("%c%c", &chx, &chy);
getchar();
scanf("%d",&e[i].w);
getchar();
e[i].x = chx - 'a'+1;
e[i].y = chy - 'a'+1;
}

qsort(e,n,sizeof(e[0]),cmp);
sum = 0;

for (i = 1; i <=n; i++)
{
x = Find_Set(e[i].x);
y = Find_Set(e[i].y);
if (x != y)
{
printf("%c - %c : %d\n",e[i].x + 'a'-1, e[i].y + 'a'-1, e[i].w);
Union(x, y, e[i].w);
}
}
printf("Total:%d\n", sum);
return 0;
}