25. K 个一组翻转链表 #
题目地址 #
解题思路 #
具体实现 #
```go
package main
import "fmt"
type ListNode struct {
Val int
Next *ListNode
}
func reverseKGroup(head *ListNode, k int) *ListNode {
// 反转链表
reverse := func(head *ListNode) *ListNode {
if head == nil {
return nil
}
var (
prev, curr, next *ListNode
)
curr = head
for curr != nil {
next = curr.Next
curr.Next = prev
prev = curr
curr = next
}
return prev
}
dummy := &ListNode{}
var (
prev, end *ListNode
)
dummy.Next = head
prev = dummy
end = dummy
for end.Next != nil {
// 把 end 往后移动 k 个位置
for i := 0; i < k && end != nil; i++ {
end = end.Next
}
if end == nil {
break
}
start := prev.Next
next := end.Next
end.Next = nil
prev.Next = reverse(start)
start.Next = next
prev = start
end = start
}
return dummy.Next
}
func main() {
ret := reverseKGroup(&ListNode{
Val: 1,
Next: &ListNode{
Val: 2,
Next: &ListNode{
Val: 3,
Next: &ListNode{
Val: 4,
Next: &ListNode{
Val: 5,
Next: nil,
},
},
},
},
}, 2)
fmt.Println(ret)
}
```