LeetCode (628. Maximum product of three numbers)

LeetCode (628. Maximum product of three numbers)

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Given an integer array, find the largest product consisting of three numbers in the array, and output this product.

Example 1:

Input: [1,2,3]
Output: 6

Example 2:

Input: [1,2,3,4]
Output: 24
Note:

The length range of the given integer array is [3,104], and the range of all elements in the array is [-1000, 1000].
The product of any three numbers in the input array will not exceed the range of 32-bit signed integers.

Link: topic link

answer:

class Solution:
    def maximumProduct(self, n: List[int]) -> int:
        ## 先倒序排序，对正数和负数分开判断
        n.sort(reverse=True)
        ## 找负数的个数,不可能取负数的三个值，所以只可能取负数的两个值
        count = 0
        ## 判断倒序后的n的前面三个和最后两个负数的大小
        for i in range(len(n)):
            if n[i]<0:
                count = len(n)-i
                if count>=2:a = n[-count:][-2:]
                break
        b = n[0]*n[1]*n[2]
        if count >=2:
            c = n[0]*a[-2]*a[-1]
            if c>=b:return c
        return b