solve problem Maximum Subarray

Author: P-ppc

README.md

@@ -143,6 +143,7 @@ All solutions will be accepted!
 |387|[First Unique Character In A String](https://leetcode-cn.com/problems/first-unique-character-in-a-string/description/)|[java/py/js](./algorithms/FirstUniqueCharacterInAString)|Easy|
 |628|[Maximum Product Of Three Numbers](https://leetcode-cn.com/problems/maximum-product-of-three-numbers/description/)|[java/py/js](./algorithms/MaximumProductOfThreeNumbers)|Easy|
 |724|[Find Pivot Index](https://leetcode-cn.com/problems/find-pivot-index/description/)|[java/py/js](./algorithms/FindPivotIndex)|Easy|
+|53|[Maximum Subarray](https://leetcode-cn.com/problems/maximum-subarray/description/)|[java/py/js](./algorithms/MaximumSubarray)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/MaximumSubarray/README.md

@@ -0,0 +1,2 @@
+# Maximum Subarray
+This problem is easy to solve, but how to use ***Divide and Conquer*** to solve it

algorithms/MaximumSubarray/Solution.java

@@ -0,0 +1,17 @@
+class Solution {
+    public int maxSubArray(int[] nums) {
+        int maxSum = Integer.MIN_VALUE,
+            curSum = Integer.MIN_VALUE;
+        
+        for (int num : nums) {
+            if (curSum >= 0 && curSum + num >= 0) {
+                curSum += num;
+            } else {
+                curSum = num;
+            }
+            maxSum = Math.max(maxSum, curSum);
+        }
+        
+        return maxSum;
+    }
+}

algorithms/MaximumSubarray/solution.js

@@ -0,0 +1,20 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxSubArray = function(nums) {
+    let maxSum = Number.MIN_SAFE_INTEGER,
+        curSum = Number.MIN_SAFE_INTEGER
+    
+    nums.forEach(num => {
+        if (curSum >= 0 && curSum + num >= 0) {
+            curSum += num
+        } else {
+            curSum = num
+        }
+        
+        maxSum = Math.max(maxSum, curSum)
+    })
+    
+    return maxSum
+};

algorithms/MaximumSubarray/solution.py

@@ -0,0 +1,16 @@
+class Solution(object):
+    def maxSubArray(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        max_sum = - sys.maxint
+        cur_sum = - sys.maxint
+        
+        for num in nums:
+            if cur_sum >= 0 and cur_sum + num >= 0:
+                cur_sum += num
+            else:
+                cur_sum = num
+            max_sum = max(max_sum, cur_sum)
+        return max_sum