Introduction

In this blog post, we will explore how to solve the LeetCode problem "2582" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

There are n people standing in a line labeled from 1 to n. The first person in the line is holding a pillow initially. Every second, the person holding the pillow passes it to the next person standing in the line. Once the pillow reaches the end of the line, the direction changes, and people continue passing the pillow in the opposite direction. For example, once the pillow reaches the nth person they pass it to the n - 1th person, then to the n - 2th person and so on. Given the two positive integers n and time, return the index of the person holding the pillow after time seconds. Example 1: Input: n = 4, time = 5 Output: 2 Explanation: People pass the pillow in the following way: 1 -> 2 -> 3 -> 4 -> 3 -> 2. After five seconds, the 2nd person is holding the pillow. Example 2: Input: n = 3, time = 2 Output: 3 Explanation: People pass the pillow in the following way: 1 -> 2 -> 3. After two seconds, the 3rd person is holding the pillow. Constraints: 2 <= n <= 1000 1 <= time <= 1000 Note: This question is the same as 3178: Find the Child Who Has the Ball After K Seconds.

Explanation

Here's the solution to the pillow-passing problem:

• Handle Cycles: Recognize that the pillow's path forms a cycle. Calculate the effective time spent within one or more complete cycles.
• Calculate Position within Cycle: Determine the pillow's position within the current cycle after accounting for full cycles.

• Adjust for Direction: If the current cycle involves movement towards the beginning of the line, adjust the position accordingly.

• Runtime Complexity: O(1), Storage Complexity: O(1)

Code

    def passThePillow(n: int, time: int) -> int:
    """
    Calculates the index of the person holding the pillow after a given time.

    Args:
        n: The number of people in the line.
        time: The number of seconds that have passed.

    Returns:
        The index of the person holding the pillow.
    """

    cycle_len = (n - 1) * 2
    time %= cycle_len

    if time < n:
        return time + 1
    else:
        return n - (time - (n - 1))