refactor 7

fishercoder1534 · fishercoder1534 · commit 448e3a928c02 · 2020-01-11T07:59:29.000-08:00
diff --git a/src/main/java/com/fishercoder/solutions/_7.java b/src/main/java/com/fishercoder/solutions/_7.java
@@ -31,11 +31,30 @@ public int reverse(int x) {
             while (x != 0) {
                 result = result * 10 + x % 10;
                 x /= 10;
+                System.out.println("result = " + result);
                 if (result > Integer.MAX_VALUE || result < Integer.MIN_VALUE) {
+                    System.out.println("break out..");
                     return 0;
                 }
             }
             return (int) result;
         }
     }
+
+    public static class Solution2 {
+        /**credit: https://leetcode.com/problems/reverse-integer/discuss/4060/My-accepted-15-lines-of-code-for-Java*/
+        public int reverse(int x) {
+            int result = 0;
+            while (x != 0) {
+                int lastDigit = x % 10;
+                int newResult = result * 10 + lastDigit;
+                if (result != (newResult - lastDigit) / 10) {
+                    return 0;
+                }
+                x /= 10;
+                result = newResult;
+            }
+            return result;
+        }
+    }
 }
diff --git a/src/test/java/com/fishercoder/_7Test.java b/src/test/java/com/fishercoder/_7Test.java
@@ -8,16 +8,26 @@
 
 public class _7Test {
     private static _7.Solution1 solution1;
+    private static _7.Solution2 solution2;
 
     @BeforeClass
     public static void setup() {
         solution1 = new _7.Solution1();
+        solution2 = new _7.Solution2();
     }
 
     @Test
     public void test1() {
-//        its reversed number is greater than Integer.MAX_VALUE, thus return 0
+        /**its reversed number is greater than Integer.MAX_VALUE, thus return 0*/
         assertEquals(0, solution1.reverse(1534236469));
+        System.out.println(Integer.MAX_VALUE);
+        System.out.println(1534236469);
+        System.out.println(Integer.MAX_VALUE - 1534236469);
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(0, solution2.reverse(1534236469));
     }
 
 }
