Given an integer array, find three numbers whose product is maximum and output the maximum product.
给一个数组，找出三个数，使得他们的乘积最大。
分类讨论 max1 max2 max3 min1 min2
1.max有3个正数 ans = max1*max2*max3
2.max有2个正数 ans = max1 * min1 * min2
3.max有1个正数 ans = max1 * min1 * min2
4.max全是负数 ans = max1 * min1 * min2
所以答案就是max(max1 * max2 * max3, max1 * min1 * min2)
class Solution(object): def maximumProduct(self, nums): """ :type nums: List[int] :rtype: int """ min1 = float(‘inf‘) min2 = float(‘inf‘) max1 = float(‘-inf‘) max2 = float(‘-inf‘) max3 = float(‘-inf‘) for value in nums: if value <= min1: min2 = min1 min1 = value elif value <= min2: min2 = value if value >= max1: max3 = max2 max2 = max1 max1 = value elif value >= max2: max3 = max2 max2 = value elif value >= max3: max3 = value return max(min1 * min2 * max1, max1 * max2 * max3)
628. Maximum Product of Three Numbers
原文：https://www.cnblogs.com/whatyouthink/p/13308102.html