python树-堆排序

代码

def heapSort(alist):
    heap = [0]
    heap.extend(alist)  # 直接将列表入堆，这样叶子节点就不需要下沉
    heapSize = len(alist)
    i = heapSize // 2  # 下沉的顺序必须是从底部到顶部
    while i > 0:  # 构建有序二叉堆
        sink(i, heap, heapSize)
        i = i - 1
    for i in range(len(alist)):
        alist[i] = delMin(heap, heapSize)
        heapSize = heapSize - 1  # 堆中元素不断减小，堆得大小也需要不断更新

def sink(index, heap, heapSize):  # 将index位置的元素沉底
    # print(heap)
    while index*2 <= heapSize:  # 保证不是叶子节点
        mi = getMin(index, heap, heapSize)  # 得到小儿子的索引
        if heap[index] > heap[mi]:
            heap[index], heap[mi] = \
            heap[mi], heap[index]
            index = mi
        else:
            break  # 如果父亲比两个儿子都小，循环停止

def getMin(index, heap, heapSize):  # 得到小儿子的索引
    if index*2+1 > heapSize:
        return index*2
    else:
        if heap[index*2] < heap[index*2+1]:
            return index*2
        else:
            return index*2+1

def delMin(heap, heapSize):  # 去顶+重构有序二叉堆
    temp = heap[1]  # 记录即将遗失的变量（返回需要用到）
    heap[1] = heap[heapSize]  # 将尾部节点移至堆顶，准备下沉
    heap.pop()
    sink(1, heap, heapSize-1)  # 下沉堆顶元素
    return temp

l1 = [5, 2, 0, 1, 3, 1, 4]
heapSort(l1)
print(l1)

体会

用函数的方法实现堆排序，由于需要调用多个函数，而且调用的函数需要多个参数，不如用类的方法简洁