152. Maximum Product Subarray

标签：Product 152 return nums int maxsofar product Subarray Math

Given an integer array nums, find a subarray that has the largest product, and return the product.

The test cases are generated so that the answer will fit in a 32-bit integer.

 

Example 1:

Input: nums = [2,3,-2,4]
Output: 6
Explanation: [2,3] has the largest product 6.

Example 2:

Input: nums = [-2,0,-1]
Output: 0
Explanation: The result cannot be 2, because [-2,-1] is not a subarray.

 

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

 

//要考虑特殊情况，即负数和负数相乘，如2，-3，-7,所以在处理乘法时，除了维护一个局部最大值，还要维护一个局部最小值。

class Solution {

    public int maxProduct(int[] nums) {

       if (nums.length == 0)

          return 0;

       if (nums.length == 1)

          return nums[0];

       int maxsofar = nums[0];

       int maxherepre = nums[0];

       int minherepre = nums[0];

       int maxhere, minhere;

       for (int i = 1; i < nums.length; i++) {

          maxhere = Math.max(Math.max(maxherepre * nums[i], minherepre * nums[i]), nums[i]);

          minhere = Math.min(Math.min(maxherepre * nums[i], minherepre * nums[i]), nums[i]);

          maxsofar = Math.max(maxhere, maxsofar);

          maxherepre = maxhere;

          minherepre = minhere;

       }

       return maxsofar;

   }

}

分享：  

标签：Product,152,return,nums,int,maxsofar,product,Subarray,Math
From： https://www.cnblogs.com/MarkLeeBYR/p/16910024.html