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## hdu 1301 Jungle Roads （最小生成树）

```/************************************************************************/
/*
最小生成树
题目大意：最小生成树，题目很长，题意很简单就是最小生成树，prim算法模拟
*/
/************************************************************************/

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <math.h>

#define MAX 0xfffffff

const int N = 30;
int map[N][N];
int vis[N];
int n;

void build_map()
{
int t = n;
char v,e;
int num,len;

for (int i = 0; i < n; i++)
for (int j = i; j < n; j++)
map[i][j] = map[j][i] = ((i==j)?0:MAX);

while(--t)
{
getchar();
v = getchar();
scanf("%d",&num);
while(num--)
{
getchar();
e = getchar();
scanf("%d",&len);
map[v-'A'][e-'A'] = map[e-'A'][v-'A'] = len;
}
}
}

int prim()
{
int t = n;
int sum = 0;
int min,k;
vis[0] = 1;
while(--t)
{
min = MAX;
for(int i = 1; i < n; i++)
{
if (vis[i] != 1 && map[0][i] < min)
{
min = map[0][i];
k = i;
}
}
vis[k] = 1;
sum += min;
for (int i = 1; i < n; i++)
{
if (vis[i] != 1 && map[k][i] < map[0][i])
map[0][i] = map[k][i];
}
}
return sum;
}

int main()
{
while(scanf("%d",&n) && n != 0)
{
build_map();
memset(vis,0,sizeof(vis));
printf("%d\n",prim());
}
return 0;
}```

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