Leetcode 92. Reverse Linked List II

文章作者:Tyan
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1. Description

Reverse Linked List II

2. Solution

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/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* reverseBetween(ListNode* head, int m, int n) {
if(m == n) {
return head;
}
ListNode* start = nullptr;
ListNode* end = nullptr;
ListNode* left = nullptr;
ListNode* right = nullptr;
ListNode* pre = nullptr;
ListNode* current = head;
ListNode* next = nullptr;
int diff = n - m + 1;
m--;
while(m) {
pre = current;
current = current->next;
m--;
}
start = pre;
right = current;
while(diff) {
next = current->next;
current->next = pre;
pre = current;
current = next;
diff--;
}
left = pre;
end = current;
right->next = end;
if(start) {
start->next = left;
return head;
}
else {
return left;
}
}
};

Reference

  1. https://leetcode.com/problems/reverse-linked-list-ii/description/
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