325. Maximum Size Subarray Sum Equals k

Author: NilStack

.DS_Store

@@ -21,6 +21,7 @@ Not only Leetcode solutions in Swift.
 * [219. Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)
 * [229. Majority Element II](https://leetcode.com/problems/majority-element-ii/)
 * [259. 3Sum Smaller](https://leetcode.com/problems/3sum-smaller)
+* [325. Maximum Size Subarray Sum Equals k](https://leetcode.com/problems/maximum-size-subarray-sum-equals-k/)
 * [349. Intersection of Two Arrays](https://leetcode.com/problems/intersection-of-two-arrays/)
 * [350. Intersection of Two Arrays II](http://www.jiuzhang.com/solutions/intersection-of-two-arrays-ii/)
 * [454. 4Sum II](https://leetcode.com/problems/4sum-ii/)

README.md

@@ -761,6 +761,39 @@ let threeSumSmallerNums = [-2, 0, 1, 3]
 let threeSumSmallerTarget = 2
 Solution.threeSumSmaller(nums: threeSumSmallerNums, threeSumSmallerTarget)
 
+/**
+ * 325. Maximum Size Subarray Sum Equals k
+ * https://leetcode.com/problems/maximum-size-subarray-sum-equals-k/
+ */
+
+extension Solution {
+    class func maxSubArrayLen(nums: [Int]?, _ k: Int) -> Int {
+        guard let nums = nums else { return 0 }
+        
+        var sum = 0
+        var res = 0
+        var m = [Int: Int]()
+        
+        for (i, num) in nums.enumerated() {
+            sum += num
+            if (sum == k) {
+               res = i + 1
+            } else if let idx = m[sum - k] {
+                res = max(res, i - idx)
+            }
+            
+            if (m[sum] == nil) {
+                m[sum] = i
+            }
+        }
+        return res
+    }
+}
+
+// usage
+let maxSubArrayLenNums = [1, -1, 5, -2, 3]
+Solution.maxSubArrayLen(nums: maxSubArrayLenNums, 3)
+
 /**
  * 349. Intersection of Two Arrays
  * https://leetcode.com/problems/intersection-of-two-arrays/