Create: 0025-reverse-nodes.rs

rust/0025-reverse-nodes-in-k-group.rs

@@ -0,0 +1,48 @@
+impl Solution {
+ pub fn reverse_k_group(head: Option<Box<ListNode>>, k: i32) -> Option<Box<ListNode>> {
+ let mut dummy = Some(Box::new(ListNode {next: head, val: 0 }));
+ let mut cur = dummy.as_mut();
+
+ 'outer: loop {
+ let mut start = cur.as_mut().unwrap().next.take();
+ if start.is_none() {
+ break 'outer;
+ }
+
+ let mut end = start.as_mut();
+ for _ in 0..(k - 1) {
+ end = end.unwrap().next.as_mut();
+
+ if end.is_none() {
+ cur.as_mut().unwrap().next = start;
+ break 'outer;
+ }
+ }
+
+ let mut tail = end.as_mut().unwrap().next.take();
+ let end = Solution::reverse(start, tail);
+ cur.as_mut().unwrap().next = end;
+
+ for _ in 0..k {
+ cur = cur.unwrap().next.as_mut()
+ }
+ }
+ dummy.unwrap().next
+ }
+
+ fn reverse(
+ mut head: Option<Box<ListNode>>,
+ tail: Option<Box<ListNode>>,
+ ) -> Option<Box<ListNode>> {
+ let mut prev = tail;
+ let mut cur = head;
+
+ while let Some(mut cur_node) = cur {
+ let mut next = cur_node.next.take();
+ cur_node.next = prev.take();
+ prev = Some(cur_node);
+ cur = next
+ }
+ prev
+ }
+}