234:回文链表

src/main/java/leetcode/editor/cn/PalindromeLinkedList.java

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+//请判断一个链表是否为回文链表。 
+//
+// 示例 1: 
+//
+// 输入: 1->2
+//输出: false 
+//
+// 示例 2: 
+//
+// 输入: 1->2->2->1
+//输出: true
+// 
+//
+// 进阶： 
+//你能否用 O(n) 时间复杂度和 O(1) 空间复杂度解决此题？ 
+// Related Topics 链表 双指针 
+// 👍 1004 👎 0
+
+package leetcode.editor.cn;
+
+import com.code.leet.entiy.ListNode;
+
+import java.util.ArrayList;
+import java.util.List;
+
+//234:回文链表
+public class PalindromeLinkedList{
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new PalindromeLinkedList().new Solution();
+    }
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public boolean isPalindrome(ListNode head) {
+        boolean bl = true;
+        List<Integer> list = new ArrayList<>();
+        while (head != null) {
+            list.add(head.val);
+            head = head.next;
+        }
+        int headIndex = 0;
+        int size = list.size();
+        while (headIndex < size - headIndex - 1) {
+            if (!list.get(headIndex).equals(list.get(size - headIndex - 1))) {
+                bl = false;
+                break;
+            }
+            headIndex++;
+        }
+        return bl;
+    }
+}
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

src/main/java/leetcode/editor/cn/PalindromeLinkedList.md

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+<p>请判断一个链表是否为回文链表。</p>
+
+<p><strong>示例 1:</strong></p>
+
+<pre><strong>输入:</strong> 1-&gt;2
+<strong>输出:</strong> false</pre>
+
+<p><strong>示例 2:</strong></p>
+
+<pre><strong>输入:</strong> 1-&gt;2-&gt;2-&gt;1
+<strong>输出:</strong> true
+</pre>
+
+<p><strong>进阶：</strong><br>
+你能否用&nbsp;O(n) 时间复杂度和 O(1) 空间复杂度解决此题？</p>
+<div><div>Related Topics</div><div><li>链表</li><li>双指针</li></div></div>\n<div><li>👍 1004</li><li>👎 0</li></div>