import edu.princeton.cs.algs4.WeightedQuickUnionUF; //导入依赖的package包/类
public Percolation(int n){// create n-by-n grid, with all sites blocked
	if (n <= 0) throw new java.lang.IllegalArgumentException("IllegalArgument");
	N = n;
	count = 0;
	uf = new WeightedQuickUnionUF(N*N + 2);
	id = new int[N+1][N+1];
	status = new int[N+1][N+1];
	for(int i = 1; i <= N; i++){
		for(int j = 1; j <= N; j++){
			id[i][j] = (i-1) * N + j-1;
			status[i][j] = 0; 
		}
	}
	virtual_top = N*N;
	virtual_bottom = N*N + 1;
}
 

import edu.princeton.cs.algs4.WeightedQuickUnionUF; //导入依赖的package包/类
/**
* create n-by-n grid, with all sites blocked
* @param n 
*           grid的大小
*/
public Percolation(int n) {
    if (n < 1)
        throw new IllegalArgumentException("Argument " + n + " is invalid.");

    this.n = n;

    //额外添加两个Virtual Site(分别为最顶端和最底部)
    wquTopModel = new WeightedQuickUnionUF(n * n + 1);
    wquBottomModel = new WeightedQuickUnionUF(n * n + 1);

    sites = new boolean[n * n];
}
 

import edu.princeton.cs.algs4.WeightedQuickUnionUF; //导入依赖的package包/类
public Percolation(int n) {
    if (n <= 0) throw new IllegalArgumentException();

    uf = new WeightedQuickUnionUF((n * n) + 2);
    isOpenSite = new boolean[(n * n) + 2];
    length = n;
    topnode = n * n;
    bottomnode = (n * n) + 1;

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < i; j++) isOpenSite[index(i + 1, j + 1)] = false;
    }
}
 

import edu.princeton.cs.algs4.WeightedQuickUnionUF; //导入依赖的package包/类
public Percolation(int n) {
	if (n <= 0)
	throw new java.lang.IllegalArgumentException("n must be > 0 !");
    this.n = n;
    virt1 = n*n;
    virt2 = n*n + 1;
    grid = new int[n][n];
    // Creates the grid plus 2 virtual sites: n² + 1 and n² + 2
    uf = new WeightedQuickUnionUF(n*n + 2);
    ufAux = new WeightedQuickUnionUF(n*n + 1);

}
 

import edu.princeton.cs.algs4.WeightedQuickUnionUF; //导入依赖的package包/类
public Percolation(int N)
{
    if (N < 1)
    {
        throw new IllegalArgumentException("N must be at least 1!");
    }

    this.N = N;

    int size = N * N;

    sites = new Site[N][N];

    uf1 = new WeightedQuickUnionUF(size + 2);

    uf2 = new WeightedQuickUnionUF(size + 1);

    top = size;

    bottom = size + 1;

    for (int i = 0; i < N; ++i)
    {
        for (int j = 0; j < N; ++j)
        {
            sites[i][j] = new Site(i, j);
        }
    }
}