v8

lib/v9/pages/sort/functions/merage.dart

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+import '../functions.dart';
+
+//快速排序
+Future<void> mergeSort(List<int> src, SortCallback callback) async {
+  await _mergeSort(src,callback,0,src.length-1);
+}
+
+///归并排序
+Future<void> _mergeSort(List<int> src, SortCallback callback,int leftIndex, int rightIndex) async {
+  // 定义一个名为 merge 的异步函数，用于合并两个有序子数组
+  Future<void> merge(int leftIndex, int middleIndex, int rightIndex) async {
+    // 计算左侧子数组和右侧子数组的大小
+    int leftSize = middleIndex - leftIndex + 1;
+    int rightSize = rightIndex - middleIndex;
+
+    // 创建左侧子数组和右侧子数组
+    List leftList = List.generate(leftSize, (index) => 0);
+    List rightList = List.generate(rightSize, (index) => 0);
+
+    // 将原始数组中的元素分别复制到左侧子数组和右侧子数组中
+    for (int i = 0; i < leftSize; i++) {
+      leftList[i] = src[leftIndex + i];
+    }
+    for (int j = 0; j < rightSize; j++) {
+      rightList[j] = src[middleIndex + j + 1];
+    }
+
+    // 初始化游标和索引
+    int i = 0, j = 0;
+    int k = leftIndex;
+
+    // 比较左侧子数组和右侧子数组的元素，并按顺序将较小的元素放入原始数组中
+    while (i < leftSize && j < rightSize) {
+      if (leftList[i] <= rightList[j]) {
+        src[k] = leftList[i];
+        i++;
+      } else {
+        src[k] = rightList[j];
+        j++;
+      }
+
+      await callback(src);
+
+      k++;
+    }
+
+    // 将左侧子数组或右侧子数组中剩余的元素放入原始数组中
+    while (i < leftSize) {
+      src[k] = leftList[i];
+      i++;
+      k++;
+
+      await callback(src);
+    }
+
+    while (j < rightSize) {
+      src[k] = rightList[j];
+      j++;
+      k++;
+
+      await callback(src);
+    }
+  }
+
+  // 如果左索引小于右索引，则递归地对数组进行归并排序
+  if (leftIndex < rightIndex) {
+    // 计算中间索引位置
+    int middleIndex = (rightIndex + leftIndex) ~/ 2;
+
+    // 分别对左侧子数组和右侧子数组进行归并排序
+    await _mergeSort(src,callback,leftIndex, middleIndex);
+    await _mergeSort(src,callback,middleIndex + 1, rightIndex);
+
+    await callback(src);
+
+    // 合并两个有序子数组
+    await merge(leftIndex, middleIndex, rightIndex);
+  }
+}