Create 0231-power-of-two.java

Author: sanajitjana

Easy/0231-power-of-two.java

@@ -0,0 +1,34 @@
+/**
+ * 231. Power of Two
+ * Difficulty: Easy
+ * URL: https://leetcode.com/problems/power-of-two/description/
+ *
+ * ---------------------
+ * Approach 1: Iterative Division
+ *
+ * - A number `n` is a power of two if it can be written as 2^k (where k ≥ 0).
+ * - If `n` is positive and divisible by 2, we keep dividing it by 2.
+ * - If after dividing repeatedly, the result becomes 1, then it was a power of two.
+ * - Otherwise, it is not.
+ *
+ * Example:
+ *   n = 16 → 16/2=8 → 8/2=4 → 4/2=2 → 2/2=1 ✅ Power of Two
+ *   n = 12 → 12/2=6 → 6/2=3 ❌ not 1 → Not a Power of Two
+ *
+ * ---------------------
+ * Time Complexity: O(log n)
+ *   - In each step we divide by 2 → about log₂(n) steps.
+ *
+ * Space Complexity: O(1)
+ *   - Only using a few variables, no extra space.
+ */
+class Solution {
+    public boolean isPowerOfTwo(int n) {
+        if (n <= 0)
+            return false;
+        while (n % 2 == 0) {
+            n = n / 2;
+        }
+        return n == 1;
+    }
+}