【代码】Java实现快速排序

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前言

Java实现快速排序（QUI）

正序

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int[] quickSort(int[] arr, int left, int right) {
    if (left < right) {
        int index = divide(arr, left, right);
        quickSort(arr, left, index - 1);
        quickSort(arr, index + 1, right);
    }
    return arr;
}

int divide(int[] arr, int left, int right) {
    int pivot = left;
    int index = left + 1;
    for (int i = index; i <= right; i++) {
        if (arr[i] < arr[pivot]) {
            int temp = arr[i];
            arr[i] = arr[index];
            arr[index] = temp;
            index++;
        }
    }
    int temp = arr[pivot];
    arr[pivot] = arr[index - 1];
    arr[index - 1] = temp;
    return index - 1;
}

void sortASC(int[] nums) {
    quickSort(nums, 0, nums.length - 1);
}

倒序

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int[] quickSort(int[] arr, int left, int right) {
    if (left < right) {
        int index = divide(arr, left, right);
        quickSort(arr, left, index - 1);
        quickSort(arr, index + 1, right);
    }
    return arr;
}

int divide(int[] arr, int left, int right) {
    int pivot = left;
    int index = left + 1;
    for (int i = index; i <= right; i++) {
        if (arr[i] > arr[pivot]) {
            int temp = arr[i];
            arr[i] = arr[index];
            arr[index] = temp;
            index++;
        }
    }
    int temp = arr[pivot];
    arr[pivot] = arr[index - 1];
    arr[index - 1] = temp;
    return index - 1;
}

void sortDESC(int[] nums) {
    quickSort(nums, 0, nums.length - 1);
}

完成