Leetcode - Reverse Linked List II
https://leetcode.com/problems/reverse-linked-list-ii/
Reverse a linked list from position m to n. Do it in one-pass.
Note: 1 ≤ m ≤ n ≤ length of list.
Example:
Input: 1->2->3->4->5->NULL, m = 2, n = 4 Output: 1->4->3->2->5->NULL
/**
* Definition for singly-linked list.
* type ListNode struct {
* Val int
* Next *ListNode
* }
*/
func reverseBetween(head *ListNode, m int, n int) *ListNode {
if m == n {
return head
}
count := 1
node := head
var head1 *ListNode
for node != nil && count != m {
count++
head1 = node
node = node.Next
}
if node == nil {
return head
}
tail1 := node
var prev2 *ListNode
for node != nil {
count++
tmp := node.Next
node.Next = prev2
prev2 = node
node = tmp
if count == n {
tmp := node.Next
node.Next = prev2
prev2 = node
node = tmp
break
}
}
tail1.Next = node
if head1 != nil {
head1.Next = prev2
} else {
return prev2
}
return head
}
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