POJ 2377(最大生成树)

#include <stdio.h>
#include <algorithm>
#include <string.h>
using namespace std;
#define maxn 1100
#define oo 0x3f3f3f3f
int maps[maxn][maxn], dist[maxn], v[maxn];
int n, m;


int Prim()
{
    memset(v, 0, sizeof(v));

    for(int i=1; i<=n; i++)
        dist[i] = maps[1][i];
        v[1] = 1;

    int sum = 0;

    for(int i=1; i<n; i++)
    {
        int index = -1, mins=-oo;

        for(int j=1; j<=n; j++)
        {
            if(!v[j] && dist[j]>mins)
            {
                mins = dist[j];
                index = j;
            }
        }

        if(mins == -1)  return -1;

        sum += mins;
        v[index] = 1;

        for(int j=1; j<=n; j++)
        {
            if(!v[j] && dist[j]<maps[index][j])
                dist[j]=maps[index][j];
        }
    }

    return sum;
}

int main()
{
    int a, b, c;
    scanf("%d %d", &n, &m);

    memset(maps, -1, sizeof(maps));

    for(int i=1; i<=m; i++)
    {
        scanf("%d %d %d", &a, &b, &c);
        maps[a][b] = maps[b][a] =max(maps[a][b], c);
    }

    int ans;
    ans = Prim();

    printf("%d\n", ans);

    return 0;
}