Algorithms, Part I WEEK1 Percolation

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能力有限，大家没思路的可以参考下。
这里写图片描述
Percolation.java

import edu.princeton.cs.algs4.WeightedQuickUnionUF;public class Percolation {    private boolean[] list;    private final int n;    private int ia;    private final WeightedQuickUnionUF UF;    private final WeightedQuickUnionUF UFTop;    public Percolation(int n)    {        this.n = n;        this.ia = 0;        list = new boolean[n * n + 1];        UF = new WeightedQuickUnionUF(n * n + 2);        UFTop = new WeightedQuickUnionUF(n * n + 1);    }    public boolean isOpen(int i, int j)    {        this.check(i, j);        return list[(i - 1) * n + j];    }    public int numberOfOpenSites()    {        return this.ia;    }    private void check(int i, int j)    {        if (i < 1 || i > n) throw new IllegalArgumentException("??");        if (j < 1 || j > n) throw new IllegalArgumentException("??");    }    private void union(int i, int j, int i1, int j1)    {        this.UF.union((i - 1) * n + j, (i1 - 1) * n + j1);        this.UFTop.union((i - 1) * n + j, (i1 - 1) * n + j1);    }    public void open(final int i, final int j)     {        this.check(i, j);        if (!this.isOpen(i, j))        {            this.ia = this.ia + 1;            list[(i - 1) * n + j] = true;            if (i == 1)             {                UF.union((i - 1) * n + j, 0);                UFTop.union((i - 1) * n + j, 0);            }            if (i == n)                UF.union((i - 1) * n + j, n * n + 1);            if (i - 1 > 0 && this.isOpen(i - 1, j))                 this.union(i, j, i-1, j);            if (i + 1 <= n && this.isOpen(i + 1, j))                 this.union(i, j, i + 1, j);            if (j + 1 <= n && this.isOpen(i, j + 1))                this.union(i, j, i, j + 1);            if (j - 1 > 0 && this.isOpen(i, j - 1))                 this.union(i, j, i, j - 1);        }    }    public boolean isFull(int i, int j)    {        check(i, j);        return UFTop.connected((i - 1) * n + j, 0);    }    public boolean percolates()    {        return UF.connected(0, n * n + 1);    }    public static void main(String[] args)    {        Percolation perc = new Percolation(3);        perc.open(1, 2);        perc.open(2, 2);        perc.open(2, 3);        System.out.println(perc.UF.find(0));        for (int i = 1; i <= 3; i++)            System.out.println(perc.UF.find((i-1)*3+1) + " " + perc.UF.find((i-1)*3+2) + " " + perc.UF.find((i-1)*3+3));        System.out.println(perc.UF.find(10));        System.out.println(perc.UFTop.find(0));        for (int i = 1; i <= 3; i++)            System.out.println(perc.UFTop.find((i-1)*3+1) + " " + perc.UFTop.find((i-1)*3+2) + " " + perc.UFTop.find((i-1)*3+3));        System.out.println(perc.percolates());        System.out.println(perc.numberOfOpenSites());    }}

PercolationStats.java

public class PercolationStats {    final private int N;    final private double[] list;    public PercolationStats(int N, int T)    {        if (N <= 0) throw new IllegalArgumentException();          if (T <= 0) throw new IllegalArgumentException();          this.N = N;        this.list = new double[T];        for (int i = 0; i < T; i++)        {            Percolation per = new Percolation(N);            double t1 = 0;            while (!per.percolates())             {                int i1 = StdRandom.uniform(N) + 1;                int j1 = StdRandom.uniform(N) + 1;                if (!per.isOpen(i1, j1))                 {                    t1 = t1 + 1;                    per.open(i1, j1);                }            }            list[i] = t1 / (N * N);        }    }    public double mean()    {        return StdStats.mean(list);    }    public double stddev()    {        return StdStats.stddev(list);    }    public double confidenceLo()     {        return this.mean() - 1.96 * this.stddev() / Math.sqrt(N);    }    public double confidenceHi()     {        return this.mean() + 1.96 * this.stddev() / Math.sqrt(N);    }    public static void main(String[] args)     {        int N = StdIn.readInt();            int T = StdIn.readInt();            PercolationStats percolationStats = new PercolationStats(N, T);            StdOut.println("mean = " + percolationStats.mean());            StdOut.println("stddev = " + percolationStats.stddev());            StdOut.println("95% confidence interval " + percolationStats.confidenceLo() + ", " + percolationStats.confidenceHi());     }}

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