Sort animation

HeapSort.java

import edu.princeton.cs.algs4.*;

public class HeapSort {
	private static int currentSinking;
	public static void sink(int[] heap, int k, int N) {
		while (2 * k <= N) {
			int j = 2 * k;
			if (j < N && heap[j] < heap[j + 1]) j++;
			if (heap[k] > heap[j]) break;// already ordered
			exch(heap, k, j);
			k = j;
		}
	}
	
	public static void exch(int[] heap, int i, int j) {
		int t = heap[i];
		heap[i] = heap[j];
		heap[j] = t;
	}
	
	public static void sort(int[] a) {
		int N = a.length - 1;
		for (int k = N / 2; k >= 1; k--) {
			sink(a, k, N);
			drawArray(a);
		}
		while (N > 1) {
			exch(a, 1, N--);
			sink(a, 1, N);
			drawArray(a);
		}
	}
	
	public static void drawArray(int[] a) {
		int n = a.length;
		StdDraw.setXscale(0, n * 2);
		StdDraw.setYscale(0, n);
		
		StdDraw.clear();
		for (int i = 1; i < n; i++) {
			double x = 1 + 2 * i;
			double y = a[i] / 2;
			double halfW = 1;
			double halfH = a[i] / 2;
			StdDraw.filledRectangle(x, y, halfW, halfH);
		}
		StdDraw.show();
	}
	
	public static void main(String[] args) {
		StdDraw.setCanvasSize(240, 160);
		StdDraw.enableDoubleBuffering();
		int[] a = new int[500];
		for (int i = 0; i < a.length; i++) {
			a[i] = i;
		}
		StdRandom.shuffle(a);
		a[0] = 0;
		HeapSort.sort(a);
		for (int x : a) {
			StdOut.printf("%d ", x);
		}
	}
}

QuickSort.java

import edu.princeton.cs.algs4.*;

public class QuickSort {
	private static int n, currentPivot, currentPi, currentPj, currentPlo, currentPhi;
	private static int frames;
	public static void sort(int[] a, int lo, int hi) {
		if (hi <= lo) return;
		
		int j = partition(a, lo, hi);
		sort(a, lo, j - 1);
		sort(a, j + 1, hi);
		currentPi = currentPj = currentPlo = currentPhi = currentPivot = -1;
		drawArray(a);
	}
	
	private static boolean less(int v, int w) {
		return v < w;
	}
	
	private static void exch(int[] a, int i, int j) {
		int t = a[i];
		a[i] = a[j];
		a[j] = t;
	}
	
	private static int partition(int[] a, int lo, int hi) {
		int i = lo, j = hi + 1;
		int pivot = a[lo];
		currentPivot = pivot;
		currentPlo = lo;
		currentPhi = hi;
		
		while (true) {
			while (less(a[++i], pivot)) if (i == hi) break;
			while (less(pivot, a[--j])) if (j == lo) break;
			if (i >= j) break;
			currentPi = i;
			currentPj = j;
			exch(a, i, j);
			drawArray(a);
		}		
		exch(a, lo, j);
		return j;
	}

	private static void drawArray(int a[]) {
		n = a.length;
		StdDraw.setXscale(0, n * 2);
		StdDraw.setYscale(0, n);
		StdDraw.enableDoubleBuffering();
		StdDraw.clear();
		for (int i = 0; i < n; i++) {
			double x = 1 + 2 * i;
			double y = a[i] / 2;
			double halfW = 1;
			double halfH = a[i] / 2;
			if (i >= currentPlo && i <= currentPhi) StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
			if (i <= currentPi && i >= currentPlo) StdDraw.setPenColor(StdDraw.BOOK_LIGHT_BLUE);
			if (i >= currentPj && i <= currentPhi) StdDraw.setPenColor(StdDraw.BOOK_BLUE);
			StdDraw.filledRectangle(x, y, halfW, halfH);
			StdDraw.setPenColor(StdDraw.BLACK);
		}
		StdDraw.setPenColor(StdDraw.BLUE);
		StdDraw.line(0, currentPivot, n * 2, currentPivot);
		StdDraw.setPenColor(StdDraw.BLACK);
		StdDraw.show();	
		if (frames % 5 == 0)
		StdDraw.save("D:\\qsa\\" + frames / 5 + ".png");
		frames++;
	}
	
	public static void main(String[] args) {
		int[] a = new int[1000];
		
		for (int i = 0; i < a.length; i++) {
			a[i] = i;
		}
		
		StdRandom.shuffle(a);
		frames = 0;
		
		StdDraw.setCanvasSize(600, 300);
		sort(a, 0, a.length - 1);
		
		for (int x : a) {
			StdOut.printf("%d ", x);
		}
	}
}