refactor 479

fishercoder1534 · fishercoder1534 · commit 72ae5fd64f71 · 2019-05-06T07:38:10.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_479.java b/src/main/java/com/fishercoder/solutions/_479.java
@@ -16,58 +16,55 @@
  The range of n is [1,8].
  */
 public class _479 {
-    /**reference: https://discuss.leetcode.com/topic/74125/java-solution-using-assumed-max-palindrom*/
-    public int largestPalindrome(int n) {
-        // if input is 1 then max is 9
-        if (n == 1) {
-            return 9;
-        }
+    public static class Solution1 {
+        /**
+         * credit: https://discuss.leetcode.com/topic/74125/java-solution-using-assumed-max-palindrom
+         */
+        public int largestPalindrome(int n) {
+            // if input is 1 then max is 9
+            if (n == 1) {
+                return 9;
+            }
 
-        // if n = 3 then upperBound = 999 and lowerBound = 99
-        int upperBound = (int) Math.pow(10, n) - 1;
-        int lowerBound = upperBound / 10;
-        long maxNumber = (long) upperBound * (long) upperBound;
+            // if n = 3 then upperBound = 999 and lowerBound = 99
+            int upperBound = (int) Math.pow(10, n) - 1;
+            int lowerBound = upperBound / 10;
+            long maxNumber = (long) upperBound * (long) upperBound;
 
-        // represents the first half of the maximum assumed palindrom.
-        // e.g. if n = 3 then maxNumber = 999 x 999 = 998001 so firstHalf = 998
-        int firstHalf = (int) (maxNumber / (long) Math.pow(10, n));
+            // represents the first half of the maximum assumed palindrom.
+            // e.g. if n = 3 then maxNumber = 999 x 999 = 998001 so firstHalf = 998
+            int firstHalf = (int) (maxNumber / (long) Math.pow(10, n));
 
-        boolean palindromFound = false;
-        long palindrom = 0;
+            boolean palindromFound = false;
+            long palindrom = 0;
 
-        while (!palindromFound) {
-            // creates maximum assumed palindrom
-            // e.g. if n = 3 first time the maximum assumed palindrom will be 998 899
-            palindrom = createPalindrom(firstHalf);
+            while (!palindromFound) {
+                // creates maximum assumed palindrom
+                // e.g. if n = 3 first time the maximum assumed palindrom will be 998 899
+                palindrom = createPalindrom(firstHalf);
 
-            // here i and palindrom/i forms the two factor of assumed palindrom
-            for (long i = upperBound; upperBound > lowerBound; i--) {
-                // if n= 3 none of the factor of palindrom  can be more than 999 or less than square root of assumed palindrom
-                if (palindrom / i > maxNumber || i * i < palindrom) {
-                    break;
-                }
+                // here i and palindrom/i forms the two factor of assumed palindrom
+                for (long i = upperBound; upperBound > lowerBound; i--) {
+                    // if n= 3 none of the factor of palindrom  can be more than 999 or less than square root of assumed palindrom
+                    if (palindrom / i > maxNumber || i * i < palindrom) {
+                        break;
+                    }
 
-                // if two factors found, where both of them are n-digits,
-                if (palindrom % i == 0) {
-                    palindromFound = true;
-                    break;
+                    // if two factors found, where both of them are n-digits,
+                    if (palindrom % i == 0) {
+                        palindromFound = true;
+                        break;
+                    }
                 }
-            }
 
-            firstHalf--;
+                firstHalf--;
+            }
+            return (int) (palindrom % 1337);
         }
-        return (int) (palindrom % 1337);
-    }
-
-    private long createPalindrom(long num) {
-        String str = num + new StringBuilder().append(num).reverse().toString();
-        return Long.parseLong(str);
-    }
 
-    public static void main(String... args) {
-        System.out.println(Long.MAX_VALUE);
-        System.out.println(Math.pow(99999999, 2) < Long.MAX_VALUE);
-        _479 test = new _479();
-        System.out.println(test.largestPalindrome(3));
+        private long createPalindrom(long num) {
+            String str = num + new StringBuilder().append(num).reverse().toString();
+            return Long.parseLong(str);
+        }
     }
 }
diff --git a/src/test/java/com/fishercoder/_479Test.java b/src/test/java/com/fishercoder/_479Test.java
@@ -6,19 +6,16 @@
 
 import static org.junit.Assert.assertEquals;
 
-/**
- * Created by stevesun on 7/19/17.
- */
 public class _479Test {
-    private static _479 test;
+    private static _479.Solution1 solution1;
 
     @BeforeClass
     public static void setup() {
-        test = new _479();
+        solution1 = new _479.Solution1();
     }
 
     @Test
     public void test1() {
-        assertEquals(123, test.largestPalindrome(3));
+        assertEquals(123, solution1.largestPalindrome(3));
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -6,19 +6,16 @@`
`6`	`6`
`7`	`7`	`import static org.junit.Assert.assertEquals;`
`8`	`8`
`9`		`-/**`
`10`		`- * Created by stevesun on 7/19/17.`
`11`		`- */`
`12`	`9`	`public class _479Test {`
`13`		`- private static _479 test;`
	`10`	`+ private static _479.Solution1 solution1;`
`14`	`11`
`15`	`12`	`@BeforeClass`
`16`	`13`	`public static void setup() {`
`17`		`- test = new _479();`
	`14`	`+ solution1 = new _479.Solution1();`
`18`	`15`	`}`
`19`	`16`
`20`	`17`	`@Test`
`21`	`18`	`public void test1() {`
`22`		`- assertEquals(123, test.largestPalindrome(3));`
	`19`	`+ assertEquals(123, solution1.largestPalindrome(3));`
`23`	`20`	`}`
`24`	`21`	`}`