From 929adbf6bbbd6f70fe94b04aeb17efb83579142e Mon Sep 17 00:00:00 2001
From: whai <lkwhai@163.com>
Date: Fri, 5 Jan 2024 22:41:13 +0800
Subject: [PATCH] --

---
 .../java/cn/whaifree/redo/LeetCode203.java    | 52 +++++++++++++++++++
 .../java/cn/whaifree/redo/LeetCode206.java    | 32 ++++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 src/main/java/cn/whaifree/redo/LeetCode203.java
 create mode 100644 src/main/java/cn/whaifree/redo/LeetCode206.java

diff --git a/src/main/java/cn/whaifree/redo/LeetCode203.java b/src/main/java/cn/whaifree/redo/LeetCode203.java
new file mode 100644
index 0000000..df615f7
--- /dev/null
+++ b/src/main/java/cn/whaifree/redo/LeetCode203.java
@@ -0,0 +1,52 @@
+package cn.whaifree.redo;
+
+
+import cn.whaifree.leetCode.model.ListNode;
+import org.junit.Test;
+
+public class LeetCode203 {
+
+    @Test
+    public void test(){
+        new Solution().removeElements(ListNode.listNodeFromArray(new int[]{1, 2}), 2).printList();
+    }
+
+
+    // 使用递归
+    /**
+     * 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 ListNode removeElements(ListNode head, int val) {
+            return delete(head, val);
+        }
+
+        // 0 1 2
+        public ListNode delete(ListNode head, int val) {
+            if (head == null) {
+                return head;
+            }
+
+            head.next = delete(head.next, val);
+            if (head.val == val) {
+                return head.next;
+            } else {
+                return head;
+            }
+        }
+
+
+
+
+
+    }
+
+}
diff --git a/src/main/java/cn/whaifree/redo/LeetCode206.java b/src/main/java/cn/whaifree/redo/LeetCode206.java
new file mode 100644
index 0000000..a3ca80c
--- /dev/null
+++ b/src/main/java/cn/whaifree/redo/LeetCode206.java
@@ -0,0 +1,32 @@
+package cn.whaifree.redo;
+
+import cn.whaifree.leetCode.model.ListNode;
+import org.junit.Test;
+
+// 递归逆转链表
+public class LeetCode206 {
+
+    @Test
+    public void test() {
+        ListNode listNode = ListNode.listNodeFromArray(new int[]{1,2,3,4,5});
+        ListNode listNode1 = new Solution().reverseList(listNode);
+        ListNode.printList(listNode1);
+    }
+
+    class Solution {
+        public ListNode reverseList(ListNode head) {
+            return reverse(null, head);
+        }
+
+        public ListNode reverse(ListNode pre, ListNode cur) {
+            if (cur == null) {
+                return pre;
+            }
+            // 只考虑三个点，1 2逆转，3（tmp 2.next）为下次递归的输入
+            ListNode tmp = cur.next;
+            cur.next = pre;
+            return reverse(cur, tmp);
+        }
+
+    }
+}