# java solution beats 88.26% with explanation

• //First we split the nums into several pieces according to the position of zeros, for example:[0,-1,2,-3,0,-4,-5,6,0,2,-3,5,-7,8,-9] is splitted into three subarrays:[-1,2,-3],[-4,-5,6],[2,-3,5,-7,8,-9].
//Then we calculate each Maximum product subarray of the nums' subarrays([-1,2,-3],[-4,-5,6],[2,-3,5,-7,8,-9]).
//The Maximum product subarray is calculated in this way:
//1. Get the numbers of negative numbers in each subarray, for example, [-1,2,-3] has two negative numbers(-1,-3),and [2,-3,5,-7,8,-9] has three negative numbers(-3,-7,-9).
//2. If the numbers of negative numbers is even, then the Maximum product subarray must be the array itself. For example, [-1,2,-3]'s Maximum product subarray is [-1,2,-3]. Its Maximum product is -1 * 2 * -3 = 6. Similarly, the Maximum product of [-4,-5,6] is 120.
//3. If the numbers of negative numbers is odd, take [2,-3,5,-7,8,-9] as an example. We first get the whole product of this array: whole = 2* -3 * 5 * -7 * 8 * -9 = -15120, then we get the first and last negative numbers in the array(first negative is -3 and last is -9). we can devide the whole by the first negative number: whole1 = whole/(2*-3) = 2520(note that we must devide 2 at first, because the subarray must be contiguous), then we can devide the whole by the last negative number: whole2 = whole/(-9) = 1680. And we compare the whole1(2520) to whole2(1680). Then we can know that the 2520 is the Maxmium product of [2,-3,5,-7,8,-9].
//4. Of course 2520>120(Maximum product of [-4,-5,6])>6(Maximum product of [-1,2,-3]). So the final result is 2520.
//5. We should also take cases such as [-2,0,-1] or [0,-2,0] into consideration.
//6. Thanks for reading (,• ₃ •,)

``````public class Solution {
public int maxProduct(int[] nums) {
if(nums.length == 0)
{
return 0;
}
if(nums.length == 1)
{
return nums[0];
}
int beginpoint = 0;
int lastpoint = 0;
int max = Integer.MIN_VALUE;
for(int i = 0;i<nums.length+1;i++)
{

if(i == nums.length||nums[i] == 0)
{
lastpoint = i;
int temp = partmaxing(beginpoint,lastpoint,nums);
beginpoint = i+1;
if(temp>max)
{
max = temp;
}
}
}
return Math.max(max,0);//for case such as:[-2,0,-1], we get max = -1. but the maximum is 0.
}
public int partmaxing(int beginpoint,int lastpoint,int[] nums)
{
if(beginpoint == lastpoint-1)
{
return nums[beginpoint];//for case such as:[-2,0,-1]
}
if(beginpoint == lastpoint)
{
return 0;//for case such as:[0,-2,0]
}
int count = 0;
int whole = 1;
Boolean firstnegetive = true;
int first = 0;
int last = 0;
for(int i = beginpoint;i<lastpoint;i++)
{
if(nums[i]<0)
{
count++;
if(firstnegetive)
{
first = i;
last = i;
firstnegetive = false;
}
else
{
last = i;
}
}
whole *= nums[i];
}
int whole1 = whole;
int whole2 = whole;
if(count%2 == 0)
{
return whole;
}
else
{
for(int i = beginpoint;i<lastpoint;i++)
{
if(i!=first)
{
whole1 /= nums[i];
}
else
{
whole1 /= nums[i];
break;
}
}
for(int i = lastpoint-1;i>beginpoint-1;i--)
{
if(i!=last)
{
whole2 /= nums[i];
}
else
{
whole2 /= nums[i];
break;
}
}
return Math.max(whole1,whole2);
}
}
}
``````

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