117笔记问答Java中常用的快速排序方法有以下几种：
- 使用递归实现的快速排序方法：
public void quickSort(int[] arr, int low, int high) {
if (low < high) {
int pivot = partition(arr, low, high);
quickSort(arr, low, pivot - 1);
quickSort(arr, pivot + 1, high);
}
}
public int partition(int[] arr, int low, int high) {
int pivot = arr[high];
int i = low - 1;
for (int j = low; j < high; j++) {
if (arr[j] < pivot) {
i++;
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
int temp = arr[i + 1];
arr[i + 1] = arr[high];
arr[high] = temp;
return i + 1;
}
- 使用栈实现的非递归快速排序方法：
public void quickSort(int[] arr, int low, int high) {
Stack stack = new Stack<>();
stack.push(low);
stack.push(high);
while (!stack.isEmpty()) {
high = stack.pop();
low = stack.pop();
int pivot = partition(arr, low, high);
if (pivot - 1 > low) {
stack.push(low);
stack.push(pivot - 1);
}
if (pivot + 1 < high) {
stack.push(pivot + 1);
stack.push(high);
}
}
}
public int partition(int[] arr, int low, int high) {
int pivot = arr[high];
int i = low - 1;
for (int j = low; j < high; j++) {
if (arr[j] < pivot) {
i++;
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
int temp = arr[i + 1];
arr[i + 1] = arr[high];
arr[high] = temp;
return i + 1;
}
这些方法都是基于快速排序的原理实现的，可以根据需要选择合适的方法来实现快速排序算法。