Add solution for leetcode #152 in javascript (#68)

* Add solution for leetcode #152 in javascript

* update readme

Co-authored-by: Chi Hi Ong <ongch@seagroup.com>

Author: ongzx

JavaScript/152.Maximum-Product-Subarray.js

@@ -0,0 +1,37 @@
+/**
+ * Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product.
+
+Example 1:
+
+Input: [2,3,-2,4]
+Output: 6
+Explanation: [2,3] has the largest product 6.
+Example 2:
+
+Input: [-2,0,-1]
+Output: 0
+Explanation: The result cannot be 2, because [-2,-1] is not a subarray.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxProduct = function (nums) {
+  if (!nums.length) return 0;
+  let maxEnding = nums[0];
+  let minEnding = nums[0];
+  let res = nums[0];
+  for (let i = 1; i < nums.length; i++) {
+    if (nums[i] < 0) {
+      let temp = minEnding;
+      minEnding = maxEnding;
+      maxEnding = temp;
+    }
+
+    maxEnding = Math.max(maxEnding * nums[i], nums[i]);
+    minEnding = Math.min(minEnding * nums[i], nums[i]);
+    res = Math.max(res, maxEnding);
+  }
+  return res;
+};

README.md

@@ -104,6 +104,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
 | 15 | [3 Sum](https://leetcode.com/problems/3sum/) | [Python](./Python/ThreeNumbersSum.py) | O( nLog(n) ) | O(1) | Medium | Array |
 | 1200 | [Minimum Absolute Difference](https://leetcode.com/problems/minimum-absolute-difference/) | [Python](./python/SmallestDifference.py) | O(n) | O(1) | Easy | Array | 
 | 532 | [K-diff Pairs in an Array](https://leetcode.com/problems/k-diff-pairs-in-an-array/) | [C++](./C++/k-diff-pairs-in-an-array.cpp) | O(n) | O(n) | Medium | Array | 
+| 152 | [Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray/) | [Javascript](./JavaScript/152.Maximum-Product-Subarray.js) | O(n) | O(n) | Medium | Array | 
 
 
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