SDUT 1488 数据结构实验：连通分量个数

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#include <bits/stdc++.h>
using namespace std;

int pre[1010];
int Find(int x);
int join(int x, int y);

int main()
{
    int n, m, k;
    cin >> k;
    while(k --)
    {
        cin >> n >>  m;
        for(int i = 1; i <= n; i++)
        {
            pre[i] = i;
        }

        for(int i = 1; i <= m; i++)
        {
            int x, y;
            cin >> x >> y;
            join(x, y);
        }
        int num = 0;
        for(int i = 1; i <= n; i++)
        {
            if(pre[i] == i)
            {
                ++num;
            }
        }
        cout << num << endl;
    }
    return 0;

}

int Find(int x)
{
    int r = x;
    while(pre[r] != r)
        r = pre[r];

    int i = x, j;
    while(i != r)
    {
        j = pre[i];
        pre[i] = r;
        i = j;
    }
   return r;
}

int join(int x, int y)
{
    int fx = Find(x), fy = Find(y);
    if(fx != fy)
    {
        pre[fx] = fy;
    }
}