初识选择排序、插入排序、希尔排序

src/main/java/App.java

@@ -1,12 +0,0 @@
-/*
- * This Java source file was generated by the Gradle 'init' task.
- */
-public class App {
-    public String getGreeting() {
-        return "Hello world.";
-    }
-
-    public static void main(String[] args) {
-        System.out.println(new App().getGreeting());
-    }
-}

src/main/java/com/cyl/algorithrms/sort/Insertion.java

@@ -0,0 +1,52 @@
+package com.cyl.algorithrms.sort;
+
+/**
+ * 插入排序
+ */
+public class Insertion {
+
+    public static void sort(Comparable[] a) {
+        //将a[]按升序排列
+        int N = a.length;
+        for (int i = 0; i < N; i++) {
+            for (int j = i; j > 0 && less(a[j], a[j-1]); j--) {
+                exch(a, j, j-1);
+            }
+        }
+    }
+
+    private static boolean less(Comparable v, Comparable w) {
+        return v.compareTo(w) < 0;
+    }
+
+    private static void exch(Comparable[] a, int i, int j) {
+        Comparable t = a[i];
+        a[i] = a[j];
+        a[j] = t;
+    }
+
+    private static void show(Comparable[] a) {
+        //    在单行中打印数组
+        for (int i = 0; i < a.length; i++) {
+            System.out.print(a[i] + " ");
+        }
+        System.out.println();
+    }
+
+    public static boolean isSorted(Comparable[] a) {
+        //    测试数组元素是否有序
+        for (int i = 1; i < a.length; i++) {
+            if(less(a[i], a[i-1])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static void main(String[] args) {
+        String[] a = "SORTEXAMPLE".split("");
+        sort(a);
+        assert isSorted(a);
+        show(a);
+    }
+}

src/main/java/com/cyl/algorithrms/sort/Selection.java

@@ -0,0 +1,56 @@
+package com.cyl.algorithrms.sort;
+
+/**
+ * 选择排序
+ */
+public class Selection {
+
+    public static void sort(Comparable[] a) {
+        //将a[]按升序排列
+        int N = a.length;
+        for (int i = 0; i < N; i++) {
+            int min = i;
+            for (int j = i + 1; j < N; j++) {
+                if(less(a[j], a[min])) {
+                    min = j;
+                }
+                exch(a, i, min);
+            }
+        }
+    }
+
+    private static boolean less(Comparable v, Comparable w) {
+        return v.compareTo(w) < 0;
+    }
+
+    private static void exch(Comparable[] a, int i, int j) {
+        Comparable t = a[i];
+        a[i] = a[j];
+        a[j] = t;
+    }
+
+    private static void show(Comparable[] a) {
+        //    在单行中打印数组
+        for (int i = 0; i < a.length; i++) {
+            System.out.print(a[i] + " ");
+        }
+        System.out.println();
+    }
+
+    public static boolean isSorted(Comparable[] a) {
+        //    测试数组元素是否有序
+        for (int i = 1; i < a.length; i++) {
+            if(less(a[i], a[i-1])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static void main(String[] args) {
+        String[] a = "SORTEXAMPLE".split("");
+        sort(a);
+        assert isSorted(a);
+        show(a);
+    }
+}

src/main/java/com/cyl/algorithrms/sort/Shell.java

@@ -0,0 +1,67 @@
+package com.cyl.algorithrms.sort;
+
+/**
+ * 希尔排序
+ */
+public class Shell {
+
+    public static void sort(Comparable[] a) {
+        //将a[]按升序排列
+        int N = a.length;
+        System.out.println("N="+N);
+        int h = 1;
+        while (h < N / 3) {
+            // 1, 4, 13, 40, 121, 364, 1093......
+            System.out.println("3*h+1之前h: "+h);
+            h = 3 * h + 1;
+            System.out.println("3*h+1之后h: "+h);
+        }
+        while (h >= 1) {
+            //将数组变为h有序
+            for (int i = h; i < N; i++) {
+                //将a[i]插入到a[i-h], a[i-2h], a[i-3*h]...之中
+                System.out.println("交换前h="+h+" i="+i);
+                for (int j = i; j >= h && less(a[j], a[j-h]); j -= h) {
+                    System.out.println("交换h="+h+" i="+i+" j="+j);
+                    exch(a, j, j-h);
+                }
+            }
+            h = h / 3;
+        }
+    }
+
+    private static boolean less(Comparable v, Comparable w) {
+        return v.compareTo(w) < 0;
+    }
+
+    private static void exch(Comparable[] a, int i, int j) {
+        Comparable t = a[i];
+        a[i] = a[j];
+        a[j] = t;
+    }
+
+    private static void show(Comparable[] a) {
+        //    在单行中打印数组
+        for (int i = 0; i < a.length; i++) {
+            System.out.print(a[i] + " ");
+        }
+        System.out.println();
+    }
+
+    public static boolean isSorted(Comparable[] a) {
+        //    测试数组元素是否有序
+        for (int i = 1; i < a.length; i++) {
+            if(less(a[i], a[i-1])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static void main(String[] args) {
+        String[] a = "SHELLSORTEXAMPLE".split("");
+        sort(a);
+        assert isSorted(a);
+        show(a);
+    }
+}

src/main/java/com/cyl/algorithrms/sort/SortTemplate.java

@@ -0,0 +1,44 @@
+package com.cyl.algorithrms.sort;
+
+/**
+ * 排序算法模板
+ */
+public abstract class SortTemplate {
+
+    public abstract void sort(Comparable[] a);
+
+    private static boolean less(Comparable v, Comparable w) {
+        return v.compareTo(w) < 0;
+    }
+
+    private static void exch(Comparable[] a, int i, int j) {
+        Comparable t = a[i];
+        a[i] = a[j];
+        a[j] = t;
+    }
+
+    private static void show(Comparable[] a) {
+    //    在单行中打印数组
+        for (int i = 0; i < a.length; i++) {
+            System.out.print(a[i] + " ");
+        }
+        System.out.println();
+    }
+
+    public static boolean isSorted(Comparable[] a) {
+    //    测试数组元素是否有序
+        for (int i = 1; i < a.length; i++) {
+            if(less(a[i], a[i-1])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static void main(String[] args) {
+        //String[] a = In.readStrings();
+        //sort(a);
+        //assert isSorted(a);
+        //show(a);
+    }
+}