Merge pull request youngyangyang04#1674 from Jack-Zhang-1314/patch-5

update 206翻转链表 about rust

Author: youngyangyang04

problems/0206.翻转链表.md

@@ -588,5 +588,45 @@ object Solution {
 
 }
 ```
+
+Rust:
+双指针法：
+
+```rust
+impl Solution {
+    pub fn reverse_list(head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
+        let mut cur = head;
+        let mut pre = None;
+        while let Some(mut node) = cur.take() {
+            cur = node.next;
+            node.next = pre;
+            pre = Some(node);
+        }
+        pre
+    }
+}
+```
+
+递归法：
+
+```rust
+impl Solution {
+    pub fn reverse_list(head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
+        fn rev(
+            mut head: Option<Box<ListNode>>,
+            mut pre: Option<Box<ListNode>>,
+        ) -> Option<Box<ListNode>> {
+            if let Some(mut node) = head.take() {
+                let cur = node.next;
+                node.next = pre;
+                pre = Some(node);
+                return rev(cur, pre);
+            }
+            pre
+        }
+        rev(head, None)
+    }
+}
+```
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