並查集

#define _CRT_SECURE_NO_DEPRECATE
#include<iostream>
#include<algorithm>
#include<string>
#include<cmath>
#include<cstdio>
using namespace std;
#define maxn 10005
struct node
{
    int x, y, w;
}e[maxn];
int n, m;
int pre[1000];
int find(int x)//查找根節點
{
    int r = x;
    while (pre[r]!=r)//返回根節點r
    {
        r = pre[r];
    }
    int i=x, j;
    while (pre[i] != r)//路徑壓縮
    {
        j = pre[i];
        pre[i] = r;
        i = j;
    }

    return r;
}
void join(int x, int y)//判斷x與y是否連通。若是不連通，就把它們所在的連通分支合併起來
{
    int fx = find(x), fy = find(y);
    if (fx != fy)
    {
        pre[fx] = fy;
    }
}
int kruskal()
{
    int res = 0, j = 0;
    //int k=1;while(k<n && j<m)n-1條邊{}if(k!=n) res=-1;return res;
    while (j < n*n)
    {
        int m1 = e[j].x, m2 = e[j].y;
        int sn1 = find(m1), sn2 = find(m2);
        if (sn1 != sn2)
        {
            res += e[j].w;
            join(sn1, sn2);
        }
        j++;
    }
    return res;
}
bool cmp(node a, node b)
{
    return a.w < b.w;
}
int t[1001];
int main()
{
    int x, y;
    while (scanf("%d", &n) != EOF && n)
    {
        for (int i = 1; i <= n; i++)
        {
            pre[i] = i;
        }
        scanf("%d", &m);
        while (m--)
        {
            scanf("%d", &x);
            pre[x] = -1;
        }
        int cost;
        int l = 0;
        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= n; j++)
            {
                scanf("%d", &cost);
                e[l].x = i;
                e[l].y = j;
                e[l].w = cost;
                l++;
            }
        }
        int sum = n*n;
        sort(e, e + sum, cmp);
        printf("%d\n", kruskal());
    }
    return 0;
}