add leetcode

Author: wave-gbt

algorithm/53. Maximum Subarray.md

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+Find the contiguous subarray within an array (containing at least one number) which has the largest sum.
+
+For example, given the array `[-2,1,-3,4,-1,2,1,-5,4]`,
+the contiguous subarray `[4,-1,2,1]` has the largest sum = `6`.
+
+**代码**
+```
+class Solution {
+    public int maxSubArray(int[] nums) {
+        int sum = nums[0];
+        int t = sum;
+        for(int i=1; i<nums.length; i++) {
+            if (t < 0) t = 0;
+            t += nums[i];
+            if (t>sum) sum = t;
+        }
+        return sum;
+    }
+}
+```