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) {
        struct ListNode *prevNode,*nextNode,*currentNode;
        prevNode = NULL;
        currentNode = head;
        nextNode = head;

        while(nextNode!=NULL)
        {
            nextNode = nextNode->next;
            currentNode->next = prevNode;
            prevNode = currentNode;
            currentNode = nextNode;
        }
        head = prevNode;
        return head;
    }
};