Create 0231-power-of-two.kt

Author: a93a

kotlin/0231-power-of-two.kt

@@ -0,0 +1,32 @@
+// iterative
+class Solution {
+    fun isPowerOfTwo(n: Int): Boolean {
+        if (n == 0) return false
+        if (n == 1) return true
+
+        var n = n
+        while (n % 2 == 0)
+            n = n shr 1
+
+        return n == 1
+    }
+}
+
+// recursive
+class Solution {
+    fun isPowerOfTwo(n: Int): Boolean {
+        if (n == 1) return true
+        if (n <= 0 || n % 2 != 0) return false
+        return isPowerOfTwo(n shr 1)
+    }
+}
+
+// one line bit manipulation
+class Solution {
+    fun isPowerOfTwo(n: Int) = (n > 0) && (n and (n - 1) == 0)
+}
+
+// one line bit manipulation
+class Solution {
+    fun isPowerOfTwo(n: Int) = (n > 0 && ((1 shl 30) % n) == 0)
+}