【LeetCode】152.Maximum Product Subarray(Medium)解题报告

【LeetCode】152.Maximum Product Subarray(Medium)解题报告

题目地址：https://leetcode.com/problems/maximum-product-subarray/description/

题目描述：

  Find the contiguous subarray within an array (containing at least one number) which has the largest product.

  For example, given the array [2,3,-2,4],the contiguous subarray [2,3] has the largest product = 6.

Solution:

//有很多种方法，暂时只看一种好理解的
//time：O(n)
//space:O(1)
//[2,3,-2,4]
//max=2 min=2 res=2
//i=1 max=6 min=3 res=6
//i=2 max=-2 min=-12 res=6
//i=3 max=4 min=-48 res=6
class Solution {
public int maxProduct(int[] nums) {
if(nums == null || nums.length==0) return 0;
//维护两个值，最大和最小
int max = nums[0];
int min = nums[0];
int res = nums[0];
for(int i=1 ; i<nums.length ; i++){
int temp = max;
max = Math.max(Math.max(max*nums[i],min*nums[i]),nums[i]);
min = Math.min(Math.min(temp*nums[i],min*nums[i]),nums[i]);
res = Math.max(res,max);
}
return res;
}
}

Date：2018年1月31日