题目描述：
求保持森林中每个村子都有道路相通，且维修所需要的最少money。
解题思路:
水题。kruskal，最小生成树问题。和原算法没神马出入。输入的时候注意下就好了（用scanf("%s")省点劲）。
代码：
#include <stdio.h>
#include <stdlib.h>
#define N 100
typedef struct{
int s;
int e;
int weight;
}ROAD;
ROAD roads[N];
int set[N];
int partition(int low, int high)
{
ROAD tmp = roads[low];
while(low<high)
{
while(low<high &&roads[high].weight >= tmp.weight)
high --;
if(low < high)
roads[low++] = roads[high];
while(low < high &&roads[low].weight <= tmp.weight)
low ++;
if(low < high)
roads[high--] = roads[low];
}
roads[low] = tmp;
return low;
}
void sort(int low, int high)
{
int index;
if(low <high)
{
index = partition(low, high);
sort(low,index-1);
sort(index+1,high);
}
}
int find_set(int i)
{
if(set[i]!=i)
set[i] = find_set(set[i]);
return set[i];
}
void union_set(int i, int j)
{
int i1 = find_set(i);
int j1 = find_set(j);
set[i1] = set[j1];
}
main()
{
int n,len,r,sum,i,j,k;
char src[10],end[10];
scanf("%d",&n);
while(n!=0)
{
r = 1;
sum = 0;
for(i=1;i<n;i++)
{
scanf("%s%d",src,&k);
for(j=1;j<=k;j++)
{
scanf("%s%d",end, &len);
roads[r].s = src[0] - 'A'+1;
roads[r].e = end[0] - 'A'+1;
roads[r++].weight = len;
}
}
len = r-1;// len条路径
sort(1,len);