［算法之排序］希尔排序算法 （java实现）

1.希尔排序算法

/*** *  * @author xiaoo_gan * 排序算法：希尔排序算法 * 实现过程：希尔排序的思想是使数组中任意间隔为h的元素都是有序的。 *     *  *  * 测试： *  input：  S H E L L S O R T E X A M P L E * output： * h = 13         第 0 轮：S H E L L S O R T E X A M P L E  * h =  4         第 1 轮：P H E L L S O R T E X A M S L E  * h =  1         第 2 轮：L E E A M H L E P S O L T S X R  * h =  0         第 3 轮：A E E E H L L L M O P R S S T X  */public class Shell {//排序算法实现public static void sort(Comparable[] a) {int N = a.length;int h = 1;int cnt = 0;while (h < N / 3) { // 增幅序列：1,4,13,40,121,364,1093,...h = 3 * h + 1;}while(h >= 1) {for (int i = h; i < N; i++) {//将a[i] 插入到a[i-h], a[i-2*h],a[i-3*h],... 中去for (int j = i; j >= h && less(a[j], a[j-h]); j -= h) { //升序//for (int j = i; j >= h && less(a[j-h], a[j]); j -= h) { //降序exch(a, j, j - h);System.out.printf("h = %2d         第 %d 轮：", h, cnt);show(a);}}System.out.println();cnt ++;h /= 3;}}//判断第一个数是否大于第二个数private static boolean less(Comparable v, Comparable w) {return v.compareTo(w) < 0;}//交换两个数的位置private static void exch(Comparable[] a, int i, int j) {Comparable t = a[i];a[i] = a[j];a[j] = t;}//打印数组private static void show(Comparable[] a) {for (int i = 0; i < a.length; i++) {System.out.print(a[i] + " ");}System.out.println();}//判断是否已排序public static boolean isSorted(Comparable[] a) {for (int i = 0; i < a.length; i++) {if (less(a[i], a[i-1])) {return false;}}return true;}public static void main(String[] args) {String[] a = {"S", "H", "E", "L", "L", "S", "O", "R", "T", "E", "X", "A", "M", "P", "L", "E"};sort(a);//排序assert isSorted(a);//判断数组是否有序//show(a);//打印数组}}

2.希尔排序算法的轨迹图

/*** *  * @author xiaoo_gan * 希尔排序的轨迹图 * 2.1.9 按照算法Insertion给出插入排序是如何将数组 E A S Y Q U E S T I O N 排序的。 */public class TraceShell {private static double row;public TraceShell() {row = 0;}private static void header(String[] a) {int N = a.length;StdDraw.setPenColor(StdDraw.BLACK);StdDraw.text(N * 3 / 7.0, -2, "希尔排序算法轨迹");StdDraw.text(-2.5, -1, "输入");for (int i = 0; i < N; i++) {StdDraw.text(i, -1, a[i]);}StdDraw.setPenColor(StdDraw.BOOK_RED);StdDraw.line(-3.5, -0.5, N - 0.5, -0.5);}public static void sort(String[] a) {int N = a.length;int h = 1;while (h < N / 3) {h = 3 * h + 1;}while (h >= 1) {boolean flag = true;for (int i = h; i < N; i++) {int min = i;for (int j = i; j >= h; j -= h) {if(less(a[j], a[j-h])) {min = j - h;exch(a, j-h, j);}}if(flag) {flag = false;StdDraw.setPenColor(StdDraw.BLACK);StdDraw.text(-2.5, row, h + "-sort");}draw(a, i, h, min);row += 0.7;}row  = row + 0.3;h /= 3;}}private static void draw(String[]a, int ith,int h, int min) {StdDraw.setPenColor(StdDraw.BLACK);for (int i = 0; i < a.length; i++) {if (i == min) {StdDraw.setPenColor(StdDraw.BOOK_RED);} else if (i > min && i <= ith && ((i - min) % h == 0)) {StdDraw.setPenColor(StdDraw.BLACK);} else {StdDraw.setPenColor(StdDraw.LIGHT_GRAY);}StdDraw.text(i, row, a[i]);}}private static boolean less(String a, String b)  {return (a.compareTo(b) < 0);}private static void exch(String[] a, int i, int j) {String swap = a[i];a[i] = a[j];a[j] = swap;}private static void footer(String[] a) {StdDraw.setPenColor(StdDraw.BLACK);StdDraw.text(-2.5, row, "输出");for (int i = 0; i < a.length; i++) {StdDraw.text(i, row, a[i]);}}public static void main(String[] args) {String s = args[0];int N = s.length();String[] a = new String[N];for (int i = 0; i < N; i++) {a[i] = s.substring(i, i + 1);}int height = 0;int h = 1;while(h < N / 3) {height += N - h + 1;h = 3 * h + 1;}height += N - h + 1;StdDraw.setCanvasSize(30 * (N + 4), 30 * (height + 3));StdDraw.setXscale(-4, N + 1);StdDraw.setYscale(height + 1, -2);StdDraw.setFont(new Font("SansSerif", Font.PLAIN, 13));header(a);sort(a);footer(a);}}