Update 0658-find-k-closest-elements.kt (Optimization)

Added solution using binary search instead of linear. Both solutions are in the file.

Author: a93a

kotlin/0658-find-k-closest-elements.kt

@@ -1,3 +1,26 @@
+/*
+* Optimized solution with binary search for the k-window instead of linear search. Time O(LogN-K) and Space O(1)
+*/
+class Solution {
+    fun findClosestElements(arr: IntArray, k: Int, x: Int): List<Int> {
+
+        var left = 0
+        var right = arr.size - k
+
+        while (left < right) {
+            val mid = (left + right) / 2
+            if (x - arr[mid] > arr[mid + k] - x)
+                left = mid + 1
+            else
+                right = mid
+        }
+
+        val res = ArrayList<Int>()
+        for(i in left until right+k) res.add(arr[i])
+        return res
+    }
+}
+
 /*
 * Linear search with window resizing. Time: O(N-K) and Space O(1) 
 */