HeapSort

class Solution{
	public static void main(String[] args) {
		int[] nums = new int[]{4,6,8,5,9};
		heapSort(nums2);
		for(int i:nums2) System.out.print(i+" ");

	}
	/**
	[4,6,8,5,9] -n/2-1-> [4,9,8,5,6] --> [9,4,8,5,6] -swap-> [6,4,8,5,9]  ([6,4,8,5][9])
	[6,4,8,5] --> [6,5,8,4] --> [8,5,6,4] -swap-> [4,5,6,8]   ([4,5,6][8][9])
	[4,5,6] --> [6,5,4] -swap->[4,5,6]    ([4,5][6][8][9])
	[4,5] --> [5,4] -swap-> [4,5] ([4][5][6][8][9])
	*/
	public static void heapSort(int[] nums){
		int n = nums.length;
		for(int i = n/2-1;i>=0;i--){
			adjustHeap(nums,i,n);
		}
		/**
		调整堆结构 + 交换堆顶与堆首的元素
		*/
		for(int j = n - 1;j>0;j--){
			// 交换 因为此时
			swap(nums,0,j);
			// 重新对堆进行调整
			adjustHeap(nums,0,j);
		}
	}
	public static void adjustHeap(int[] nums,int index,int len){
		int t = nums[index];
		for(int i = 2*index+1;i<len;i=2*i+1){
			if(i+1 < len && nums[i+1] > nums[i]){
				i++;
			}
			if(nums[i] > t){
				nums[index] = nums[i];
				index = i;
			}else{
				break;
			}
		}
		nums[index] = t;;

	}
	public static void swap(int[] nums ,int i,int j){
		int t = nums[i];
		nums[i] = nums[j];
		nums[j] = t;
	}

}