feat: added leetcode 53 java solution (Tahanima#108)

Author: Tahanima

Algorithms/Medium/53_MaximumSubarray/Solution.java

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