update code

src/main/java/git/snippet/mergesort/Code_MergeSort.java

@@ -10,52 +10,48 @@ package git.snippet.mergesort;
 //归并排序的实质是把比较行为变成了有序信息并传递，比O(N^2)的排序快
 // 笔记：https://www.cnblogs.com/greyzeng/p/16653063.html
 public class Code_MergeSort {
-
     // 递归方法实现
-    public static void mergeSort1(int[] arr) {
+    public static void sort1(int[] arr) {
         if (null == arr || arr.length <= 1) {
             return;
         }
-        process(arr, 0, arr.length - 1);
+        p(arr, 0, arr.length - 1);
     }
 
-    public static void process(int[] arr, int l, int r) {
-        if (l == r) {
+    public static void p(int[] arr, int l, int r) {
+        if (l >= r) {
             return;
         }
-        // 求中点
-        int mid = l + ((r - l) >> 1);
-        // 左边部分有序
-        process(arr, l, mid);
-        // 右边部分有序
-        process(arr, mid + 1, r);
-        // 整体变有序
-        merge(arr, l, mid, r);
+        int m = l + ((r - l) >> 1);
+        p(arr, l, m);
+        p(arr, m + 1, r);
+        m(arr, l, m, r);
     }
 
-    private static void merge(int[] arr, int l, int m, int r) {
-        int[] helper = new int[r - l + 1];
-        int index = 0;
-        int ls = l;
-        int rs = m + 1;
-        while (ls <= m && rs <= r) {
-            if (arr[ls] > arr[rs]) {
-                helper[index++] = arr[rs++];
+    public static void m(int[] arr, int l, int m, int r) {
+        int[] help = new int[r - l + 1];
+        int s = l;
+        int e = m + 1;
+        int i = 0;
+        while (s <= m && e <= r) {
+            if (arr[s] < arr[e]) {
+                help[i++] = arr[s++];
             } else {
-                helper[index++] = arr[ls++];
+                help[i++] = arr[e++];
             }
         }
-        while (ls <= m) {
-            helper[index++] = arr[ls++];
+        while (s <= m) {
+            help[i++] = arr[s++];
         }
-        while (rs <= r) {
-            helper[index++] = arr[rs++];
+        while (e <= r) {
+            help[i++] = arr[e++];
         }
-        for (int i = 0; i < helper.length; i++) {
-            arr[l + i] = helper[i];
+        for (int k = 0; k < help.length; k++) {
+            arr[l + k] = help[k];
         }
     }
 
+
     // 非递归方法实现
     public static void mergeSort2(int[] arr) {
         if (null != arr && arr.length > 1) {
@@ -79,4 +75,28 @@ public class Code_MergeSort {
             }
         }
     }
+
+
+    private static void merge(int[] arr, int l, int m, int r) {
+        int[] helper = new int[r - l + 1];
+        int index = 0;
+        int ls = l;
+        int rs = m + 1;
+        while (ls <= m && rs <= r) {
+            if (arr[ls] > arr[rs]) {
+                helper[index++] = arr[rs++];
+            } else {
+                helper[index++] = arr[ls++];
+            }
+        }
+        while (ls <= m) {
+            helper[index++] = arr[ls++];
+        }
+        while (rs <= r) {
+            helper[index++] = arr[rs++];
+        }
+        for (int i = 0; i < helper.length; i++) {
+            arr[l + i] = helper[i];
+        }
+    }
 }

src/test/java/git/snippet/mergesort/Code_MergeSortTest.java

@@ -11,31 +11,35 @@ import static git.snippet.common.Generator.generateRandomArray;
 
 @DisplayName("归并排序")
 public class Code_MergeSortTest {
+
     @Test
-    public void mergeSortTest1() {
+    @DisplayName("归并排序递归解法测试")
+    public void mergeSortTest2() {
         int times = 500000; // 测试的次数
         int maxSize = 100; // 数组的最大长度是100
         int maxValue = 100; // 数组元素的大小[-100,100]
         for (int i = 0; i < times; i++) {
             int[] arr1 = generateRandomArray(maxSize, maxValue);
             int[] arr4 = copyArray(arr1);
-            Code_MergeSort.mergeSort2(arr1);
+            Code_MergeSort.sort1(arr1);
             Arrays.sort(arr4);
             Assertions.assertArrayEquals(arr1, arr4);
         }
     }
 
     @Test
-    public void mergeSortTest2() {
+    @DisplayName("归并排序非递归解法测试")
+    public void mergeSortTest1() {
         int times = 500000; // 测试的次数
         int maxSize = 100; // 数组的最大长度是100
         int maxValue = 100; // 数组元素的大小[-100,100]
         for (int i = 0; i < times; i++) {
             int[] arr1 = generateRandomArray(maxSize, maxValue);
             int[] arr4 = copyArray(arr1);
-            Code_MergeSort.mergeSort1(arr1);
+            Code_MergeSort.mergeSort2(arr1);
             Arrays.sort(arr4);
             Assertions.assertArrayEquals(arr1, arr4);
         }
     }
+
 }
\ No newline at end of file