hdu1879 继续畅通工程 基础最小生成树

#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <cmath>
using namespace std;

#define  MAXN 10005
int fa[MAXN];
struct node
{
    int from, to, len;
}arr[MAXN];

bool cmp(node a, node b)
{
    return a.len < b.len;
}

int m;

int find(int x)
{
    if (x == fa[x])
        return x;
    else
        return fa[x] = find(fa[x]);
}

int main()
{
    int n;
    while (scanf("%d",&n)&&n)
    {
        for (int i = 0; i <= n; i++)
            fa[i] = i;
        m = 0;
        int s = n*(n - 1) / 2;
        for (int i = 0; i < s; i++)
        {
            int a, b, c, d;
            scanf("%d%d%d%d", &a, &b, &c, &d);
            if (d)
            {
                int x = find(a);
                int y = find(b);
                if (x != y)
                    fa[y] = x;
            }
            else
            {
                arr[m].from = a;
                arr[m].to = b;
                arr[m].len = c;
                m++;
            }
        }

        sort(arr, arr + m, cmp);
        int ans = 0;
        for (int i = 0; i < m; i++)
        {
            int a = find(arr[i].from);
            int b = find(arr[i].to);
            if (a != b)
            {
                ans += arr[i].len;
                fa[b] = a;
            }
        }
        printf("%d\n", ans);
    }
    //system("pause");
    return 0;
}