堆排序算法实现

堆排序算法代码实现

class HeapSort {

    public static void main(String[] args) {
        int[] src = {1, 5, 7, 2, 3, 8, 27, 19,1, 5, 7, 2, 3, 8, 27, 19,1, 5, 7, 2, 3, 8, 27, 19,1, 5, 7, 2, 3, 8, 27, 19,1, 5, 7, 2, 3, 8, 27, 19};
        heapSort(src);
        for(int num : src){
            System.out.print(num + " ");
        }

    }
    public static void heapSort(int[] nums){
        buildMaxHeap(nums,nums.length);
        for(int i = nums.length - 1; i >= 0; i--){
            swap(nums,i,0);
            buildMaxHeap(nums,i);
        }
    }
    public static void buildMaxHeap(int[] nums,int length){
        for(int i = (length - 2) / 2; i >= 0; i--){
            maxHeapfy(nums,i,length - 1);
        }
    }
    public static void maxHeapfy(int[] nums,int index,int end){

        if(index >= end){
            return;
        }
        int max = index;

        int left = index * 2 + 1;
        int right = index * 2 + 2;
        if(left <= end && nums[left] > nums[max])
            max = left;
        if(right <= end && nums[right] > nums[max])
            max = right;
        if(max != index) {
            swap(nums, index, max);
            maxHeapfy(nums, max, end);
        }

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