152. Maximum Product Subarray

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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.

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按0分成几段每段最大值在这几个之间出 1.全乘起来 2.第一个负数及之前的除外剩下的全乘起来 3.最后一个负数及之后的除外，剩下的全乘起来然后再所有这些值里取最大的

public class Solution {    public int maxProduct(int[] nums) {        int ret = Integer.MIN_VALUE;        if(nums.length==1)return nums[0];        ret = nums[0];        int i = 0;        while(i<nums.length){            int cheng1 = 1;            int cheng2 = 1;            int start = 0;//第一个负数之后开始乘            while(i<nums.length&&nums[i]!=0){                cheng1*=nums[i];                if(start==1)cheng2*=nums[i];                if(cheng1>ret)ret = cheng1;                if(start==1&&cheng2>ret)ret=cheng2;                if(nums[i]<0)start=1;                i++;            }            if(i<nums.length&&nums[i]==0&&ret<0)ret=0;            i++;        }        return ret;    }}

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