排序-堆排序

思路直接看我录制的视频吧 算法-堆排序_哔哩哔哩_bilibili

实现代码如下所示：

class Solution {
    public int[] sortArray(int[] nums) {
        if (nums == null || nums.length == 1) {
            return nums;
        }
        headSort(nums);
        return nums;
    }

    private void headSort(int[] nums) {
        for (int i = (nums.length - 1) / 2; i >=0; i--) {
            adjustHead(nums, i, nums.length);
        }
        for (int i = nums.length - 1; i >0; i--) {
            int temp = nums[i];
            nums[i] = nums[0];
            nums[0] = temp;
            adjustHead(nums, 0, i);
        }
    }

    private void adjustHead(int[] nums, int parent, int length) {
        int temp = nums[parent];
        int maxChildIndex = parent * 2 + 1;
        while (maxChildIndex < length) {
            int rightChild = maxChildIndex + 1;
            if (rightChild < length && nums[rightChild] > nums[maxChildIndex]) {
                maxChildIndex++;
            }
            if (maxChildIndex < length && nums[maxChildIndex] < temp) {
                break;
            }
            nums[parent] = nums[maxChildIndex];
            parent = maxChildIndex;
            maxChildIndex = maxChildIndex * 2 + 1;
        }
        nums[parent] = temp;
    }
}