628. Maximum Product of Three Numbers数组中三个数乘积最大

Given an integer array, find three numbers whose product is maximum and output the maximum product.

Example 1:

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

Example 2:

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

Note:

1. The length of the given array will be in range [3,10⁴] and all elements are in the range [-1000, 1000].
2. Multiplication of any three numbers in the input won't exceed the range of 32-bit signed integer.

题目解释：数组中任意三个数乘积，找到这个乘积的最大值。需要考虑的是数组中可能含有负数，所以解题思路就是将数组进行升序排序，然后如果数组有负数，即在前几个元素处，故只需要比较前两个数的成绩和倒数二和倒数第三个数的乘积的大小即可。

class Solution {    public int maximumProduct(int[] nums) {        if(nums==null||nums.length<=2)return 0;        Arrays.sort(nums);        int n=nums.length;        if(nums[0]*nums[1]<nums[n-2]*nums[n-3]){            return nums[n-1]*nums[n-2]*nums[n-3];        }else return nums[0]*nums[1]*nums[n-1];    }}