public class HeapSort {
    private static void heapSort(int[] arr) {
        // 構(gòu)造初始堆（大頂堆）,從第一個(gè)非葉子節(jié)點(diǎn)開(kāi)始調(diào)整,左右孩子節(jié)點(diǎn)中較大的交換到父節(jié)點(diǎn)中
        for (int i = arr.length / 2 - 1; i >= 0; i--) {
            heapAdjust(arr, i, arr.length);
        }
        // 調(diào)整堆結(jié)構(gòu)，交換堆頂元素與末尾元素
        for (int j = arr.length - 1; j > 0; j--) {
            swap(arr, 0, j);// 將堆頂元素與末尾元素進(jìn)行交換
            heapAdjust(arr, 0, j);// 重新對(duì)堆進(jìn)行調(diào)整
        }
    }
 
    private static void swap(int[] arr, int a, int b) {
        int temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }
 
    // 調(diào)整大頂堆
    private static void heapAdjust(int[] arr, int i, int len) {
        int temp = arr[i], index = 2 * i + 1;
        while (index < len) {
            if (index + 1 < len && arr[index] < arr[index + 1]) {// 如果左子結(jié)點(diǎn)小于右子結(jié)點(diǎn)，index指向右子結(jié)點(diǎn)
                index += 1;
            }
            if (arr[index] > temp) {// 如果子節(jié)點(diǎn)大于父節(jié)點(diǎn)，將子節(jié)點(diǎn)值賦給父節(jié)點(diǎn)
                arr[i] = arr[index];
                i = index;
                index = 2 * i + 1;
            } else {
                break;
            }
        }
        arr[i] = temp;
    }
 
    public static void main(String[] args) {
        int[] arr = {1,28,3,21,11,7,6,18};
        heapSort(arr);
        System.out.println(Arrays.toString(arr));
    }
}