zoj 3204 Connect them

最小生成树，我用的是并查集+贪心的写法。

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
using namespace std;
const int maxn = ;
int c[maxn][maxn];
int father[maxn];
int flag[maxn];
struct abc{
    int fei, a, b;
}dt[maxn*maxn];
struct ans{
    int aa, bb;
}anss[maxn*maxn];
bool cmp(const abc&a, const abc&b)
{
    if (a.fei == b.fei&&a.a == b.a) return a.b < b.b;
    if (a.fei == b.fei) return a.a < b.a;
    return a.fei < b.fei;
}
bool cmp2(const ans&a, const ans&b)
{
    if (a.aa == b.aa) return a.bb < b.bb;
    return a.aa < b.aa;
}
int find(int x)
{
    if (x != father[x]) father[x] = find(father[x]);
    return father[x];
}
int main()
{
    int sb;
    scanf("%d", &sb);
    while (sb--)
    {
        int n, i, j;
        scanf("%d", &n);
        memset(c, , sizeof(c));
        memset(father, , sizeof(father));
        memset(flag, , sizeof(flag));
        int q = ;
        for (i = ; i <= ; i++) father[i] = i;
        for (i = ; i <= n; i++) for (j = ; j <= n; j++) scanf("%d", &c[i][j]);
        for (i = ; i <= n; i++)
        {
            for (j = i + ; j <= n; j++)
            {
                if (c[i][j] != )
                {
                    dt[q].a = i;
                    dt[q].b = j;
                    dt[q].fei = c[i][j];
                    q++;
                }
            }
        }
        sort(dt, dt + q, cmp);
        int qq = ;
        for (i = ; i < q; i++)
        {
            int x = find(dt[i].a);
            int y = find(dt[i].b);
            if (x != y)
            {
                father[x] = y;
                anss[qq].aa = dt[i].a;
                anss[qq].bb = dt[i].b;
                qq++;
            }
        }
        for (i = ; i <= n; i++){int u = find(i);flag[u]++;}
        int dd = ;
        for (i = ; i <= n; i++){if (flag[i] >  && flag[i] == n){dd = ;break;}}
        if (dd==)
        {
            sort(anss, anss + qq, cmp2);
            for (i = ; i < qq; i++)
            {
                if (i < qq-)printf("%d %d ", anss[i].aa, anss[i].bb);
                else printf("%d %d\n", anss[i].aa, anss[i].bb);
            }
        }
        else if (dd == ) printf("-1\n");
    }
    return ;
}