LeetCode Daily Question (858. Mirror Reflection)

There is a special square room with mirrors on each of the four walls. Except for the southwest corner, there are receptors on each of the remaining corners, numbered 0, 1, and 2.

The square room has walls of length p and a laser ray from the southwest corner first meets the east wall at a distance q from the 0th receptor.

Given the two integers p and q, return the number of the receptor that the ray meets first.

The test cases are guaranteed so that the ray will meet a receptor eventually.

Example 1:

Input: p = 2, q = 1
Output: 2

Explanation: The ray meets receptor 2 the first time it gets reflected back to the left wall.

Example 2:

Input: p = 3, q ​​= 1
Output: 1

Constraints:

• 1 <= q <= p <= 1000

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Imagine the room as an elevator, all the heights of m * p (m is an integer greater than 0) of the elevator are hung with sensors on the left and right sides, 2 and 1 on the odd floor, 2 and 0 on the even floor, and then thisThe problem becomes the problem of finding the least common multiple

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impl Solution {pub fn mirror_reflection(p: i32,span> q: i32) -> i32 {let mut m = 1;let mut is_up = true;loop {if p * m % q == 0 {if p * m / q % 2 == 0span> {return 2;}if is_up {return 1;}return 0;}m += 1;is_up = !is_up;}}}