reverse number

realDuYuanChao · realDuYuanChao · commit 5e233307ea87 · 2020-10-07T11:15:48.000+08:00
diff --git a/src/main/java/com/examplehub/maths/LeapYear.java b/src/main/java/com/examplehub/maths/LeapYear.java
@@ -0,0 +1,14 @@
+package com.examplehub.maths;
+
+public class LeapYear {
+
+    /**
+     * Test if a year is leap year.
+     *
+     * @param year the year to be checked.
+     * @return {@code true} if the year is leap year, otherwise {@code false}.
+     */
+    public static boolean isLeapYear(int year) {
+        return year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
+    }
+}
diff --git a/src/main/java/com/examplehub/maths/ReverseNumber.java b/src/main/java/com/examplehub/maths/ReverseNumber.java
@@ -0,0 +1,19 @@
+package com.examplehub.maths;
+
+public class ReverseNumber {
+
+    /**
+     * Reverse a number.
+     *
+     * @param number the number to be reversed.
+     * @return the reversed number of given number.
+     */
+    public static int reverse(int number) {
+        int reversedNumber = 0;
+        while (number != 0) {
+            reversedNumber = reversedNumber * 10 + number % 10;
+            number /= 10;
+        }
+        return reversedNumber;
+    }
+}
diff --git a/src/test/java/com/examplehub/maths/LeapYearTest.java b/src/test/java/com/examplehub/maths/LeapYearTest.java
@@ -0,0 +1,17 @@
+package com.examplehub.maths;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class LeapYearTest {
+
+    @Test
+    void testLeapYear() {
+        assertTrue(LeapYear.isLeapYear(1600));
+        assertTrue(LeapYear.isLeapYear(2000));
+        assertFalse(LeapYear.isLeapYear(1700));
+        assertFalse(LeapYear.isLeapYear(1800));
+        assertFalse(LeapYear.isLeapYear(1900));
+    }
+}
diff --git a/src/test/java/com/examplehub/maths/ReverseNumberTest.java b/src/test/java/com/examplehub/maths/ReverseNumberTest.java
@@ -0,0 +1,17 @@
+package com.examplehub.maths;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ReverseNumberTest {
+    @Test
+    void testReverseNumber() {
+        assertEquals(21, ReverseNumber.reverse(12));
+        assertEquals(12345, ReverseNumber.reverse(54321));
+        assertEquals(54321, ReverseNumber.reverse(12345));
+
+        assertEquals(-21, ReverseNumber.reverse(-12));
+        assertEquals(-54321, ReverseNumber.reverse(-12345));
+    }
+}
