206-Reverse-Linked-List.cpp

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */

class Solution {
public:
    ListNode* reverseList(ListNode* head) {

        ListNode* prev = NULL;
        ListNode* curr = head;

        while(curr != NULL){
            ListNode* forward = curr->next;
            curr->next = prev;
            prev = curr;
            curr = forward;
            
        }
        return prev;
    }
};