[LeetCode] 206. Reverse Linked List

😎문제

1. 빈 노드일 경우 null 반환
2. prev, current, next 선언
3. ListNode를 순회하며 역순 정렬
4. 역순 정렬된 head 반환(prev)

function reverseList(head: ListNode | null): ListNode | null {
    if (!head) return null;

    let prev: ListNode | null = null;
    let current: ListNode | null = head;
    let next: ListNode | null = null;

    while (current) {
        next = current.next; 
        current.next = prev;
        prev = current;    
        current = next;    
    }

    return prev;
}