refactor 141

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_141.java

@@ -8,10 +8,28 @@
 /**
  * 141. Linked List Cycle
 
-Given a linked list, determine if it has a cycle in it.
+ Given a linked list, determine if it has a cycle in it.
+ To represent a cycle in the given linked list, we use an integer
+ pos which represents the position (0-indexed) in the linked list where tail connects to.
+ If pos is -1, then there is no cycle in the linked list.
 
-Follow up:
-Can you solve it without using extra space?
+ Example 1:
+ Input: head = [3,2,0,-4], pos = 1
+ Output: true
+ Explanation: There is a cycle in the linked list, where tail connects to the second node.
+
+ Example 2:
+ Input: head = [1,2], pos = 0
+ Output: true
+ Explanation: There is a cycle in the linked list, where tail connects to the first node.
+
+ Example 3:
+ Input: head = [1], pos = -1
+ Output: false
+ Explanation: There is no cycle in the linked list.
+
+ Follow up:
+ Can you solve it using O(1) (i.e. constant) memory?
  */
 public class _141 {
 

src/test/java/com/fishercoder/_141Test.java

@@ -0,0 +1,29 @@
+package com.fishercoder;
+
+import com.fishercoder.common.utils.LinkedListUtils;
+import com.fishercoder.solutions._141;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _141Test {
+    private static _141.Solution1 solution1;
+    private static _141.Solution2 solution2;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _141.Solution1();
+        solution2 = new _141.Solution2();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(false, solution1.hasCycle(LinkedListUtils.contructLinkedList(new int[]{1, 2, 3, 4})));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(false, solution2.hasCycle(LinkedListUtils.contructLinkedList(new int[]{1, 2, 3, 4})));
+    }
+}