poj1258

简单题

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

#define inf 0x3f3f3f3f
#define maxn 105

int vis[maxn];
int lowc[maxn];
int cost[maxn][maxn];
int n;

void input()
{
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            scanf("%d", &cost[i][j]);
}

int prim()
{
    int i, j, p;
    int minc, res = 0;
    memset(vis, 0, sizeof(vis));
    vis[0] = 1;
    for (i = 0; i < n; i++)
        lowc[i] = cost[0][i];
    for (i = 1; i < n; i++)
    {
        minc = inf;
        p = -1;
        for (j = 0; j < n; j++)
            if (0 == vis[j] && minc > lowc[j])
            {
                minc = lowc[j];
                p = j;
            }
        if (inf == minc)
            return -1;
        res += minc;
        vis[p] = 1;
        for (j = 0; j < n; j++)
            if (0 == vis[j] && lowc[j] > cost[p][j])
                lowc[j] = cost[p][j];
    }
    return res;
}

int main()
{
    //freopen("t.txt", "r", stdin);
    while (scanf("%d", &n) != EOF)
    {
        input();
        printf("%d\n", prim());
    }
    return 0;
}