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Commit e304b36

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feat: update go solutions to lc problem: No.0025
No.0025.Reverse Nodes in k-Group
1 parent 9969c49 commit e304b36

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3 files changed

+142
-88
lines changed

3 files changed

+142
-88
lines changed

‎solution/0000-0099/0025.Reverse Nodes in k-Group/README.md‎

Lines changed: 60 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -50,6 +50,14 @@
5050

5151
<!-- 这里可写通用的实现逻辑 -->
5252

53+
**方法一:迭代**
54+
55+
时间复杂度为 $O(n),ドル空间复杂度为 $O(1),ドル其中 $n$ 是链表的长度。
56+
57+
**方法二:递归**
58+
59+
时间复杂度为 $O(n),ドル空间复杂度为 $O(\log _k n),ドル其中 $n$ 是链表的长度。
60+
5361
<!-- tabs:start -->
5462

5563
### **Python3**
@@ -244,6 +252,8 @@ function reverseKGroup(head: ListNode | null, k: number): ListNode | null {
244252

245253
### **Go**
246254

255+
迭代:
256+
247257
```go
248258
/**
249259
* Definition for singly-linked list.
@@ -253,40 +263,64 @@ function reverseKGroup(head: ListNode | null, k: number): ListNode | null {
253263
* }
254264
*/
255265
func reverseKGroup(head *ListNode, k int) *ListNode {
256-
dummy := &ListNode{0, head}
257-
pre := dummy
258-
cur := dummy
259-
for cur.Next != nil {
260-
for i := 0; i < k && cur != nil; i++ {
266+
var dummy *ListNode = &ListNode{}
267+
p, cur := dummy, head
268+
for cur != nil {
269+
start := cur
270+
for i := 0; i < k; i++ {
271+
if cur == nil {
272+
p.Next = start
273+
return dummy.Next
274+
}
261275
cur = cur.Next
262276
}
263-
if cur == nil {
264-
return dummy.Next
265-
}
266-
t := cur.Next
267-
cur.Next = nil
268-
start := pre.Next
269-
pre.Next = reverseList(start)
270-
start.Next = t
271-
pre = start
272-
cur = pre
277+
p.Next, p = reverse(start, cur), start
273278
}
274279
return dummy.Next
275280
}
276281

277-
func reverseList(head *ListNode) *ListNode {
278-
if head == nil || head.Next == nil {
279-
return head
282+
func reverse(start, end *ListNode) *ListNode {
283+
var pre *ListNode = nil
284+
for start != end {
285+
tmp := start.Next
286+
start.Next, pre = pre, start
287+
start = tmp
280288
}
281-
dummyHead := &ListNode{}
282-
cur := head
283-
for cur != nil {
284-
tmp := cur.Next
285-
cur.Next = dummyHead.Next
286-
dummyHead.Next = cur
287-
cur = tmp
289+
return pre
290+
}
291+
```
292+
293+
递归:
294+
295+
```go
296+
/**
297+
* Definition for singly-linked list.
298+
* type ListNode struct {
299+
* Val int
300+
* Next *ListNode
301+
* }
302+
*/
303+
func reverseKGroup(head *ListNode, k int) *ListNode {
304+
start, end := head, head
305+
for i := 0; i < k; i++ {
306+
if end == nil {
307+
return head
308+
}
309+
end = end.Next
310+
}
311+
res := reverse(start, end)
312+
start.Next = reverseKGroup(end, k)
313+
return res
314+
}
315+
316+
func reverse(start, end *ListNode) *ListNode {
317+
var pre *ListNode = nil
318+
for start != end {
319+
tmp := start.Next
320+
start.Next, pre = pre, start
321+
start = tmp
288322
}
289-
return dummyHead.Next
323+
return pre
290324
}
291325
```
292326

‎solution/0000-0099/0025.Reverse Nodes in k-Group/README_EN.md‎

Lines changed: 66 additions & 32 deletions
Original file line numberDiff line numberDiff line change
@@ -39,6 +39,14 @@
3939

4040
## Solutions
4141

42+
**Approach 1: Iteration**
43+
44+
Time complexity $O(n),ドル Space complexity $O(1)$.
45+
46+
**Approach 2: Recursion**
47+
48+
Time complexity $O(n),ドル Space complexity $O(\log _k n)$.
49+
4250
<!-- tabs:start -->
4351

4452
### **Python3**
@@ -229,6 +237,8 @@ function reverseKGroup(head: ListNode | null, k: number): ListNode | null {
229237

230238
### **Go**
231239

240+
Iteration:
241+
232242
```go
233243
/**
234244
* Definition for singly-linked list.
@@ -238,40 +248,64 @@ function reverseKGroup(head: ListNode | null, k: number): ListNode | null {
238248
* }
239249
*/
240250
func reverseKGroup(head *ListNode, k int) *ListNode {
241-
dummy := &ListNode{0, head}
242-
pre := dummy
243-
cur := dummy
244-
for cur.Next != nil {
245-
for i := 0; i < k && cur != nil; i++ {
246-
cur = cur.Next
247-
}
248-
if cur == nil {
249-
return dummy.Next
250-
}
251-
t := cur.Next
252-
cur.Next = nil
253-
start := pre.Next
254-
pre.Next = reverseList(start)
255-
start.Next = t
256-
pre = start
257-
cur = pre
258-
}
259-
return dummy.Next
251+
var dummy *ListNode = &ListNode{}
252+
p, cur := dummy, head
253+
for cur != nil {
254+
start := cur
255+
for i := 0; i < k; i++ {
256+
if cur == nil {
257+
p.Next = start
258+
return dummy.Next
259+
}
260+
cur = cur.Next
261+
}
262+
p.Next, p = reverse(start, cur), start
263+
}
264+
return dummy.Next
260265
}
261266

262-
func reverseList(head *ListNode) *ListNode {
263-
if head == nil ||head.Next == nil {
264-
return head
265-
}
266-
dummyHead := &ListNode{}
267-
cur := head
268-
for cur != nil {
269-
tmp := cur.Next
270-
cur.Next = dummyHead.Next
271-
dummyHead.Next = cur
272-
cur = tmp
273-
}
274-
return dummyHead.Next
267+
func reverse(start, end *ListNode) *ListNode {
268+
var pre *ListNode = nil
269+
for start != end {
270+
tmp := start.Next
271+
start.Next, pre = pre, start
272+
start = tmp
273+
}
274+
return pre
275+
}
276+
```
277+
278+
Recursion:
279+
280+
```go
281+
/**
282+
* Definition for singly-linked list.
283+
* type ListNode struct {
284+
* Val int
285+
* Next *ListNode
286+
* }
287+
*/
288+
func reverseKGroup(head *ListNode, k int) *ListNode {
289+
start, end := head, head
290+
for i := 0; i < k; i++ {
291+
if end == nil {
292+
return head
293+
}
294+
end = end.Next
295+
}
296+
res := reverse(start, end)
297+
start.Next = reverseKGroup(end, k)
298+
return res
299+
}
300+
301+
func reverse(start, end *ListNode) *ListNode {
302+
var pre *ListNode = nil
303+
for start != end {
304+
tmp := start.Next
305+
start.Next, pre = pre, start
306+
start = tmp
307+
}
308+
return pre
275309
}
276310
```
277311

‎solution/0000-0099/0025.Reverse Nodes in k-Group/Solution.go‎

Lines changed: 16 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -6,38 +6,24 @@
66
* }
77
*/
88
func reverseKGroup(head *ListNode, k int) *ListNode {
9-
dummy := &ListNode{0, head}
10-
pre := dummy
11-
cur := dummy
12-
for cur.Next != nil {
13-
for i := 0; i < k && cur != nil; i++ {
14-
cur = cur.Next
9+
start, end := head, head
10+
for i := 0; i < k; i++ {
11+
if end == nil {
12+
return head
1513
}
16-
if cur == nil {
17-
return dummy.Next
18-
}
19-
t := cur.Next
20-
cur.Next = nil
21-
start := pre.Next
22-
pre.Next = reverseList(start)
23-
start.Next = t
24-
pre = start
25-
cur = pre
14+
end = end.Next
2615
}
27-
return dummy.Next
16+
res := reverse(start, end)
17+
start.Next = reverseKGroup(end, k)
18+
return res
2819
}
2920

30-
func reverseList(head *ListNode) *ListNode {
31-
if head == nil || head.Next == nil {
32-
return head
33-
}
34-
dummyHead := &ListNode{}
35-
cur := head
36-
for cur != nil {
37-
tmp := cur.Next
38-
cur.Next = dummyHead.Next
39-
dummyHead.Next = cur
40-
cur = tmp
21+
func reverse(start, end *ListNode) *ListNode {
22+
var pre *ListNode = nil
23+
for start != end {
24+
tmp := start.Next
25+
start.Next, pre = pre, start
26+
start = tmp
4127
}
42-
return dummyHead.Next
43-
}
28+
return pre
29+
}

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