LeetCode-in-All
152. Maximum Product Subarray
Medium
Given an integer array nums, find a contiguous non-empty subarray within the array that has the largest product, and return the product.
It is guaranteed that the answer will fit in a 32-bit integer.
A subarray is a contiguous subsequence of the array.
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.
Constraints:
1 <= nums.length <= 2 * 104-10 <= nums[i] <= 10- The product of any prefix or suffix of
numsis guaranteed to fit in a 32-bit integer.
Solution
class Solution {
/**
* @param Integer[] $nums
* @return Integer
*/
public function maxProduct($arr) {
$ans = PHP_INT_MIN;
$cprod = 1;
foreach ($arr as $j) {
$cprod = $cprod * $j;
$ans = max($ans, $cprod);
if ($cprod == 0) {
$cprod = 1;
}
}
$cprod = 1;
for ($i = count($arr) - 1; $i >= 0; $i--) {
$cprod = $cprod * $arr[$i];
$ans = max($ans, $cprod);
if ($cprod == 0) {
$cprod = 1;
}
}
return $ans;
}
}