并查集简单实现

class UnionFind {
    
    
  int[] data;

  public UnionFind(int n) {
    
    
    data = new int[n];
    for (int i = 0; i < data.length; i++) {
    
    
      data[i] = i;
    }
  }

  private int findRoot(int cur) {
    
    
    //路劲压缩，避免查找树过长
    return cur == data[cur] ? cur : (data[cur] = findRoot(data[cur]));
  }

  public void union(int a, int b) {
    
    
    data[findRoot(a)] = findRoot(b);
  }

  public boolean isSame(int a, int b) {
    
    
    return findRoot(a) == findRoot(b);
  }
}