refactor 342

fishercoder1534 · fishercoder1534 · commit 5dfbb1d1fd8b · 2019-01-14T08:06:18.000-08:00
diff --git a/src/main/java/com/fishercoder/solutions/_342.java b/src/main/java/com/fishercoder/solutions/_342.java
@@ -1,62 +1,50 @@
 package com.fishercoder.solutions;
-/**342. Power of Four
-Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
 
-Example:
-Given num = 16, return true. Given num = 5, return false.
-
-Follow up: Could you solve it without loops/recursion?*/
+/**
+ * 342. Power of Four
+ *
+ * Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
+ *
+ * Example:
+ * Given num = 16, return true. Given num = 5, return false.
+ * Follow up: Could you solve it without loops/recursion?
+ * */
 public class _342 {
-    //with my original idea in the bottom, just dive a little bit deeper, you can realize that another important feature of a number
-    //that is power of four is that its only single one bit must appear on the odd position, and power of two won't meet this requirement
-    //decimal number 8 has binary format: 0000-0000-0000-0000-0000-0000-0000-1000
-    //decimal number 16 has binary format: 0000-0000-0000-0000-0000-0000-0001-0000
-    //hex number 0x55555555 has binary format: 1010-1010-1010-1010-1010-1010-1010-1010
-    //thus, doing AND with 0x55555 will check if the only one bit is located on the odd position, thus ruling out those that are power of 2 but not power of 4
-    public boolean isPowerOfFour_bit_manipulation(int num) {
-        return (num > 0 && 1073741824 % num == 0 && (num & 0x55555555) != 0);
+    public static class Solution1 {
+        //Just dive a little bit deeper, you can realize that another important feature of a number
+        //that is power of four is that its only single one bit must appear on the odd position, and power of two won't meet this requirement
+        //decimal number 8 has binary format: 0000-0000-0000-0000-0000-0000-0000-1000
+        //decimal number 16 has binary format: 0000-0000-0000-0000-0000-0000-0001-0000
+        //hex number 0x55555555 has binary format: 1010-1010-1010-1010-1010-1010-1010-1010
+        //thus, doing AND with 0x55555 will check if the only one bit is located on the odd position, thus ruling out those that are power of 2 but not power of 4
+        public boolean isPowerOfFour(int num) {
+            return (num > 0 && 1073741824 % num == 0 && (num & 0x55555555) != 0);
+        }
     }
 
-    public boolean isPowerOfFour_base_conversion(int num) {
-        //^ means to match the beginning of a line
-        //$ means to match the end of a line
-        //* means zero or more of the preceding character
-        return Integer.toString(num, 4).matches("^10*$");
+    public static class Solution2 {
+        public boolean isPowerOfFour(int num) {
+            //^ means to match the beginning of a line
+            //$ means to match the end of a line
+            //* means zero or more of the preceding character
+            return Integer.toString(num, 4).matches("^10*$");
+        }
     }
 
-    //a regular loop method to make it AC'ed
-    public boolean isPowerOfFour(int num) {
-        if (num < 4 && num != 1) {
-            return false;
-        }
-        while (num != 1) {
-            if (num % 4 != 0) {
+    public static class Solution3 {
+        //a regular loop method to make it AC'ed
+        public boolean isPowerOfFour(int num) {
+            if (num < 4 && num != 1) {
                 return false;
             }
-            num /= 4;
-        }
-        return true;
-    }
-
-    //simply using the max number possible that is power of 4 won't work for this case, because, that number is a power of 2, but might
-    //not be a power of 4, e.g. number 8
-    public boolean isPowerOfFour_not_accepted(int num) {
-        return (num > 3 && 1073741824 % num == 0);
-    }
-
-    public static void main(String... strings) {
-        int temp = 4;
-        int maxPowerOf4 = 4;
-        while (temp > 0) {
-            temp *= 4;
-            if (temp > 0) {
-                maxPowerOf4 = temp;
+            while (num != 1) {
+                if (num % 4 != 0) {
+                    return false;
+                }
+                num /= 4;
             }
+            return true;
         }
-        System.out.println("maxPowerOf4 is: " + maxPowerOf4);
-
-
-        System.out.println(Integer.parseInt("55555555", 16));
-        System.out.println(Integer.toBinaryString(Integer.parseInt("55555555", 16)));
     }
+
 }
