79 lines
2.2 KiB
Dart
79 lines
2.2 KiB
Dart
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);
|
|
}
|
|
} |