add kotlin solution for 918. Maximum Sum Circular Subarray

Author: technophilist

kotlin/0918-maximum-sum-circular-subarray.kt

@@ -0,0 +1,22 @@
+class Solution {
+    fun maxSubarraySumCircular(nums: IntArray): Int {
+        if (nums.size == 1) return nums[0]
+        // max sum
+        var totalSum = nums[0]
+        var maxSum = nums[0]
+        var currentMaxSum = nums[0]
+        // minSum
+        var minSum = nums[0]
+        var currentMinSum = nums[0]
+        for (i in 1..nums.lastIndex) {
+            // max sum computation
+            currentMaxSum = maxOf(nums[i], currentMaxSum + nums[i])
+            maxSum = maxOf(maxSum, currentMaxSum)
+            // minSum computation
+            currentMinSum = minOf(nums[i], currentMinSum + nums[i])
+            minSum = minOf(minSum, currentMinSum)
+            totalSum += nums[i]
+        }
+        return if (minSum != totalSum) maxOf((totalSum - minSum), maxSum) else maxSum
+    }
+}