最小的K个数 牛客网 剑指Offer

最小的K个数 牛客网 剑指Offer

• 题目描述
• 输入n个整数，找出其中最小的K个数。例如输入4,5,1,6,2,7,3,8这8个数字，则最小的4个数字是1,2,3,4,。

class Solution:
    #run:33ms memory:5732k
    def GetLeastNumbers_Solution(self, tinput, k):
        if tinput == None or len(tinput) < k or len(tinput) <= 0 or k <=0:
            return []
        list_size = len(tinput)
        start = 0
        end = list_size - 1
        index = self.QuickSelect(tinput, list_size, start, end)
        while index != k-1:
            if index > k-1:
                end = index - 1
                index = self.QuickSelect(tinput, list_size, start, end)
            else:
                start = index + 1
                index = self.QuickSelect(tinput, list_size, start, end)
        output = tinput[:k]
        output.sort()
        return output

    def QuickSelect(self,numbers,length,start,end):
        if numbers == None or length <= 0 or start < 0 or end >= length:
            return None
        if end == start:
            return end
        pivotvlue = numbers[start]
        leftmark = start + 1
        rightmark = end
        while True:
            while numbers[leftmark] <= pivotvlue and leftmark <= rightmark:
                leftmark += 1
            while numbers[rightmark] >= pivotvlue and rightmark >= leftmark:
                rightmark -= 1
            if leftmark >= rightmark:
                break
            else:
                numbers[leftmark], numbers[rightmark] = numbers[rightmark], numbers[leftmark]
        numbers[rightmark], numbers[start] = numbers[start], numbers[rightmark]
        return rightmark