通过：poj-1287

#include <stdio.h>
#include <iostream>
#include <string.h>
#include <algorithm>
#include <math.h>
#include <stack>
#include <queue>

using namespace std;
#define INF 10000000

int n, m;
int a, b, c;

int map[100][100], dis[100], v[100];

int prim(int n)
{
	int i, j, k, min, sum = 0;
	for (i = 1; i <= n; i++)
		dis[i] = map[1][i];

	memset(v, 0, sizeof(v));
	v[1] = 1;
	dis[1] = 0;

	for (i = 2; i <= n; i++)
	{
		k = 1;
		min = INF;
		for (j = 1; j <= n; j++)
			if (!v[j] && min>dis[j])
			{
				k = j;
				min = dis[j];
			}
		sum += min;
		v[k] = 1;
		for (j = 1; j <= n; j++)
			if (!v[j] && dis[j]>map[k][j])
				dis[j] = map[k][j];
	}
	return sum;
}

int main()
{
	while (scanf("%d %d", &n, &m) != EOF )
	{
		if (n == 0)
			break;
		for (int i = 1; i <= n; i++)
			for (int j = 1; j <= n; j++)
				map[i][j] = INF;

		while (m--)
		{
			scanf("%d%d%d",&a,&b,&c);
			if (map[a][b] >= c)
			{
				map[a][b] = map[b][a] = c;
			}
		}
		printf("%d\n",prim(n));
	}
	return 0;
}

图论——最小生成树