Rotate Right Algorithm Analysis

function rotateRight<T = number>(
    head: ListNode<T> | null,
    k: number
): ListNode<T> | null {
    // Step 1: エッジケースの処理
    if (!head || !head.next || k === 0) {
        return head;
    }
    
    // Step 2: 長さと末尾を特定
    const { length, tail } = findLengthAndTail(head);
    
    // Step 3: 実際の回転数を計算
    const actualRotations = k % length;
    if (actualRotations === 0) {
        return head;
    }
    
    // Step 4: 新しい末尾を見つける
    const newTail = findNewTail(head, length - actualRotations - 1);
    
    // Step 5: 新しい先頭を設定
    const newHead = newTail.next;
    
    // Step 6: ポインタを付け替え
    newTail.next = null;    // 新しい末尾
    tail.next = head;       // 循環を作成
    
    return newHead;
}

function findLengthAndTail<T>(
    head: NonNullListNode<T>
): { length: number; tail: ListNode<T> } {
    let length = 1;
    let current = head;
    
    while (current.next) {
        current = current.next;
        length++;
    }
    
    return { length, tail: current };
}

function findNewTail<T>(head: ListNode<T>, steps: number): ListNode<T> {
    let current = head;
    
    for (let i = 0; i < steps; i++) {
        if (!current.next) {
            throw new Error('Internal error: unexpected end of list');
        }
        current = current.next;
    }
    
    return current;
}