reverse linked list (examplehub#92)

realDuYuanChao · github-actions · web-flow · commit 18032f692d31 · 2021-04-01T20:30:40.000+08:00
* reverse-linked-list

* Formatted with Google Java Formatter

Co-authored-by: github-actions &lt;${GITHUB_ACTOR}@users.noreply.github.com&gt;
diff --git a/src/main/java/com/examplehub/leetcode/easy/ReverseLinkedList.java b/src/main/java/com/examplehub/leetcode/easy/ReverseLinkedList.java
@@ -0,0 +1,18 @@
+package com.examplehub.leetcode.easy;
+
+import com.examplehub.leetcode.ListNode;
+
+/** https://leetcode.com/problems/reverse-linked-list/ */
+public class ReverseLinkedList {
+  public static ListNode solution1(ListNode head) {
+    ListNode prev = null;
+    ListNode cur = head;
+    while (cur != null) {
+      ListNode nextTemp = cur.next;
+      cur.next = prev;
+      prev = cur;
+      cur = nextTemp;
+    }
+    return prev;
+  }
+}
diff --git a/src/test/java/com/examplehub/leetcode/easy/ReverseLinkedListTest.java b/src/test/java/com/examplehub/leetcode/easy/ReverseLinkedListTest.java
@@ -0,0 +1,21 @@
+package com.examplehub.leetcode.easy;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.examplehub.leetcode.ListNode;
+import com.examplehub.utils.NodeUtils;
+import org.junit.jupiter.api.Test;
+
+class ReverseLinkedListTest {
+  @Test
+  void testSolution1() {
+    ListNode head = NodeUtils.makeList(1, 2, 3, 4, 5);
+    assertEquals("5->4->3->2->1", ReverseLinkedList.solution1(head).toString());
+
+    head = NodeUtils.makeList(1, 2);
+    assertEquals("2->1", ReverseLinkedList.solution1(head).toString());
+
+    head = NodeUtils.makeList();
+    assertSame(null, ReverseLinkedList.solution1(head));
+  }
+}
