Published Sep 27, 2019
[
Reverse a singly linked list.
Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL
prev and curtempNext as a temporary storage/**
* Definition for singly-linked list.
* class ListNode {
* val: number
* next: ListNode | null
* constructor(val?: number, next?: ListNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
* }
*/
function reverseList(head: ListNode | null): ListNode | null {
if(head === null || head.next === null) {
return head;
}
let left: ListNode = null, right: ListNode = head;
while(right !== null){
const temp: ListNode = right.next;
right.next = left;
left = right;
right = temp;
}
return left;
};
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* reverseList(ListNode* head) {
ListNode* prev = nullptr;
ListNode* cur = head;
while(cur != nullptr){
// Assign temporary value first
auto tempNext = cur->next;
cur->next = prev;
prev = cur;
// Assign loop control variable last
cur = tempNext;
}
return prev;
}
};
References: