reverseListNode.cpp

#include <iostream>
#include <vector>

struct ListNode {
    int val;
    ListNode* next;
    ListNode(): ListNode(0, nullptr) {}
    ListNode(int x): ListNode(x, nullptr) {}
    ListNode(int x, ListNode* next): val(x), next(next) {}
};

void Traverse(ListNode* head) {
    std::cout << "[";
    if (head != nullptr) {
        std::cout << head->val;
        head = head->next;
    }
    while (head != nullptr) {
        std::cout << ", " << head->val;
        head = head->next;
    }
    std::cout << "]" << std::endl;
}

ListNode* GenerateListFromVector(const std::vector<int>& arr) {
    ListNode dummy;
    ListNode* prev = &dummy;
    for (auto& val : arr) {
        prev->next = new ListNode(val);
        prev = prev->next;
    }

    return dummy.next;
}

ListNode* ReverseInterval(ListNode* head, int left, int right) {
    return head;
}

int main() {
// case 1:
//   input:
//     [1, 2, 3, 4, 5]
//     1
//     5
//   output:
//     [5, 4, 3, 2, 1]
//
    auto* head1 = GenerateListFromVector({1, 2, 3, 4, 5});
    head1 = ReverseInterval(head1, 1, 5);
    Traverse(head1);

// case 2:
//   input:
//     [1, 2, 3, 4, 5]
//     1
//     2
//   output:
//     [2, 1, 3, 4, 5]
//
//
    auto* head2 = GenerateListFromVector({1, 2, 3, 4, 5});
    head2 = ReverseInterval(head2, 1, 2);
    Traverse(head2);

// case 3:
//   input:
//     [1, 2, 3, 4, 5]
//     2
//     4
//   output:
//     [1, 4, 3, 2, 5]
    auto* head3 = GenerateListFromVector({1, 2, 3, 4, 5});
    head3 = ReverseInterval(head3, 2, 4);
    Traverse(head3);

    return 0;
}