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.

思路：乘積最大，則肯定是尋找三個絕對值最大的數相乘。所以先把數組排序，這樣數值最大的數為最後三個。第一反應應該會認為

數組末尾三個數乘積就是答案了。但是數組裏可能還會有負數，如果數組最開頭兩個數是負數，且絕對值很大，則答案可能是頭兩個數

和數組末尾的那個數相乘；

1 class Solution {
2     public int maximumProduct(int[] nums) {
3         Arrays.sort(nums);
4         int p = nums.length;
5         int product1 = nums[p-1]*nums[p-2]*nums[p-3];
 
6         int product2 = nums[p-1]*nums[0]*nums[1];
7         return product1>product2?product1:product2;
8     }
9 }

[Leetcode]628. Maximum Product of Three Numbers