checks given number is power of 2 or not

CodingBlocks Training/Day8/PowerOf2Check.java

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+// Bit-Masking
+
+package Lecture8;
+
+public class PowerOf2Check {
+
+	public static void main(String[] args) {
+
+		int num = 1;
+		System.out.println(checkPowerOf2(num));
+
+		System.out.println(powerCheck2(num));
+	}
+
+	// 1st approach ~ inefficient one -> O(logn)
+	public static boolean powerCheck2(int n) {
+		if (n != 0 && n != 1){
+			while (n > 1) {
+				n = n / 2;
+				// System.out.println(n);
+			}
+			if (n == 1) {
+				return true;
+			} else {
+				return false;
+			}
+		}
+		return false;
+	}
+
+	// 2nd approach ~ efficient solution -> O(1)
+	public static boolean checkPowerOf2(int n) {
+		if (n != 0 && n != 1) {
+			if ((n & (n - 1)) == 0) {
+				return true;
+			}
+		}
+		return false;
+	}
+
+}