@@ -114,4 +114,82 @@ impl MyLinkedList {
114114
115115## 学习感想
116116
117- 也没啥好说的，rust只要写出来，基本是对的，没有用take的形式，而是全部去除了option用ref
117+ 也没啥好说的，rust只要写出来，基本是对的，没有用take的形式，而是全部去除了option用ref
118+
119+
120+ ``` rust
121+ struct MyLinkedList {
122+ head : Option <Box <ListNode >>,
123+ cnt : i32 ,
124+ }
125+
126+ struct ListNode {
127+ val : i32 ,
128+ next : Option <Box <ListNode >>,
129+ }
130+
131+ /**
132+ * `&self` means the method takes an immutable reference.
133+ * If you need a mutable reference, change it to `&mut self` instead.
134+ */
135+ impl MyLinkedList {
136+
137+ fn new () -> Self {
138+ Self {
139+ head : None ,
140+ cnt : 0i32 ,
141+ }
142+ }
143+
144+ fn get (& self , mut index : i32 ) -> i32 {
145+ if index >= self . cnt { return - 1i32 }
146+ let mut ptr : & Box <ListNode > = self . head. as_ref (). unwrap ();
147+ while index > 0i32 {
148+ ptr = ptr . next. as_ref (). unwrap ();
149+ index -= 1i32 ;
150+ }
151+ ptr . val
152+ }
153+
154+ fn add_at_head (& mut self , val : i32 ) {
155+ self . add_at_index (0i32 , val );
156+ }
157+
158+ fn add_at_tail (& mut self , val : i32 ) {
159+ self . add_at_index (self . cnt, val );
160+ }
161+
162+ fn add_at_index (& mut self , mut index : i32 , val : i32 ) {
163+ if index > self . cnt { return }
164+ let mut ptr : & mut Option <Box <ListNode >> = & mut self . head;
165+ while index > 0i32 {
166+ ptr = & mut ptr . as_mut (). unwrap (). next;
167+ index -= 1i32 ;
168+ }
169+ self . cnt += 1i32 ;
170+ * ptr = Some (Box :: new (ListNode { val : val , next : ptr . take () }))
171+ }
172+
173+ fn delete_at_index (& mut self , mut index : i32 ) {
174+ if index >= self . cnt { return }
175+ let mut ptr : & mut Option <Box <ListNode >> = & mut self . head;
176+ while index > 0i32 {
177+ ptr = & mut ptr . as_mut (). unwrap (). next;
178+ index -= 1i32 ;
179+ }
180+ let nxt : Option <Box <ListNode >> = ptr . take (). unwrap (). next. take ();
181+ * ptr = nxt ;
182+ self . cnt -= 1i32 ;
183+ }
184+ }
185+
186+ /**
187+ * Your MyLinkedList object will be instantiated and called as such:
188+ * let obj = MyLinkedList::new();
189+ * let ret_1: i32 = obj.get(index);
190+ * obj.add_at_head(val);
191+ * obj.add_at_tail(val);
192+ * obj.add_at_index(index, val);
193+ * obj.delete_at_index(index);
194+ */
195+ ```
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