LeetCode # Array # Easy # 628. Maximum Product of Three Numbers

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

题目：给定一个数组，数组长度3-10000，求其中三个数乘积最大的值；（最大乘积不会超过int范围）

思路：这个题和求第三个最大数的思路一样，但是要注意如果有负数，则两个负数乘积为正。所以要用两个变量存储两个最小数。

 1 class Solution {
 2     public int maximumProduct(int[] nums) {
 3       int m = nums.length;
 4       if(m == 3){
 5     　　  return nums[0]*nums[1]*nums[2];
 6       }
 7       int first= 0,second=0,third=0;
 8       int min1 = Integer.MAX_VALUE, min2= Integer.MAX_VALUE;
 9       for(int n :nums ){
10         if(n > first){
11           third = second;
12           second = first;
13           first = n;
14         }else if(n > second){
15           third = second;
16          second = n;
17        }else{
18          if(n > third) {
19            third = n;
20          }
21        }
22        if(n < min1){
23          min2 = min1;
24          min1 = n;
25        }else if(n < min2){
26          min2 = n;
27        }
28      }
29      return Math.max(first*second*third,first*min1*min2);
30     }
31 }