Maximum Product Subarray

Desicription

Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product.

Example 1:

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

Example 2:

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

Solution

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class Solution {
public:
int maxProduct(vector<int>& nums) {
int res = nums[0];
for(int i = 1, maxNum = res, minNum = res; i < nums.size(); i++) {
if(nums[i] < 0)
swap(maxNum, minNum);
maxNum = max(nums[i], maxNum * nums[i]);
minNum = min(nums[i], minNum * nums[i]);
res = max(res, maxNum);
}
return res;
}
};