Fibonacci Number

FibonacciNumber.cpp

#include <vector>
#include <iostream>

using namespace std;

// 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) {
        return (head == NULL) ? NULL : doit(head);
    }

    ListNode* doit(ListNode* node) {
        if (node->next != NULL) {
            ListNode* head = doit(node->next);
            ListNode* newNode = new ListNode(node->val);
            ListNode* iterator = head;
            while(iterator->next != NULL) {
                iterator = iterator->next;
            }
            iterator->next = newNode;
            return head;
        } else {
            return new ListNode(node->val);
        }
    }
};

int main(int argc, char**argv) {
    
    auto a = ListNode(1);
    auto b = ListNode(3);
    auto c = ListNode(4);
    auto d = ListNode(2);

    a.next = &b;
    b.next = &c;
    c.next = &d;
    
    auto obj = Solution();

    ListNode* p = obj.reverseList(&a);

    ListNode* iterator = p;
    while(iterator != NULL) {
        cout << iterator->val << endl;
        iterator = iterator->next;
    }

    return 0;
}