add binary search on kotlin

01_introduction_to_algorithms/kotlin/BinarySearch.kt

@@ -0,0 +1,21 @@
+fun List<Int>.binarySearch(item: Int) : Int? {
+    var min = 0
+    var max = lastIndex
+    while (min <= max) {
+        val mid = (min + max)/2
+        val guess = this[mid]
+        if (guess == item) return mid
+        if (guess > item) max = mid -1
+        else min = mid + 1
+    }
+    return null
+}
+
+
+val sortedArray = (0..100 step 3).toList()
+
+
+fun main(args: Array<String>) {
+    print(sortedArray.binarySearch(6))
+}
+