算法--堆排序

2023年12月18日 160次阅读 来源: jke_zq

原理：堆分为最大堆和最小堆。采用数组存放，其左右子树分别是I2,I2+1,不断调整父节点比左右子节点最大（小）关系,直至到数组末尾。每次调整完整个数组，则数组index=1的值为最大（小），将其与数组最后一位swap。然后重新调整除最后一位的剩余的数使之成为最大（小）堆，然后再次和倒数第二位交换，依次进行。

python 代码：

# -*- coding: utf-8 -*-
from random import randint

#generate a unsorted list
origin = []

def randomList():
    for i in xrange(0,10,1):
        origin.append(randint(-10,10))
    #最大连续子序列的和
    print origin
    return origin

#without the recursion
def head_adjust_while(origin, i, size):
    maxIndex = i
    while maxIndex * 2 < size:
        left = maxIndex * 2
        right = maxIndex * 2 + 1
        oldMaxIndex = maxIndex
        if origin[left] > origin[maxIndex]:
            maxIndex = left
        if right < size and origin[right] > origin[maxIndex]:
            maxIndex = right
        if maxIndex != oldMaxIndex:
            origin[maxIndex] = origin[maxIndex] + origin[oldMaxIndex]
            origin[oldMaxIndex] = origin[maxIndex] - origin[oldMaxIndex]
            origin[maxIndex] = origin[maxIndex] - origin[oldMaxIndex]
        else:
            break


def head_adjust_recursion(origin, i, size):
    maxIndex = i
    leftIndex = 2*i
    rightIndex = 2*i + 1
    if leftIndex < size and origin[leftIndex] > origin[maxIndex]:
        maxIndex = leftIndex
    if rightIndex < size and origin[rightIndex] > origin[maxIndex]:
        maxIndex = rightIndex
    if maxIndex != i:
        origin[i] = origin[maxIndex] + origin[i]
        origin[maxIndex] = origin[i] - origin[maxIndex]
        origin[i] = origin[i] - origin[maxIndex]
        head_adjust_recursion(origin, maxIndex, size)

def build_heap(origin):
    size = len(origin)
    for i in xrange(size/2,0,-1):
        # head_adjust_recursion(origin,i,size)
        head_adjust_while(origin, i, size)

def heap_sortion():
    origin = randomList()
    build_heap(origin)
    size = len(origin)
    for i in xrange(1,size-1):
        origin[1] = origin[1] + origin[size-i]
        origin[size-i] = origin[1] - origin[size-i]
        origin[1] = origin[1] - origin[size-i]
        # head_adjust_recursion(origin, 1, size-i)
        head_adjust_while(origin, 1, size - i)
    print origin

if __name__ == "__main__":
    heap_sortion()
    原文作者：jke_zq
    原文地址: https://segmentfault.com/a/1190000000504962
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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