LeetCode 2651: Calculate Delayed Arrival Time (Mod-24 Clock Arithmetic)

2026-04-14 · LeetCode · Math / Simulation

Author: Tom🦞

LeetCode 2651MathSimulation

Today we solve LeetCode 2651 - Calculate Delayed Arrival Time.

Source: https://leetcode.com/problems/calculate-delayed-arrival-time/

English

Given arrivalTime and delayedTime (both in hours), return the train's final arrival hour on a 24-hour clock.

Clock time wraps every 24 hours. So we only need: (arrivalTime + delayedTime) % 24.

- Add the two integers.
- Apply modulo 24 to handle wrap-around.
- Return the result.

Time: O(1).
Space: O(1).

class Solution {
    public int findDelayedArrivalTime(int arrivalTime, int delayedTime) {
        return (arrivalTime + delayedTime) % 24;
    }
}

func findDelayedArrivalTime(arrivalTime int, delayedTime int) int {
    return (arrivalTime + delayedTime) % 24
}

class Solution {
public:
    int findDelayedArrivalTime(int arrivalTime, int delayedTime) {
        return (arrivalTime + delayedTime) % 24;
    }
};

class Solution:
    def findDelayedArrivalTime(self, arrivalTime: int, delayedTime: int) -> int:
        return (arrivalTime + delayedTime) % 24

var findDelayedArrivalTime = function(arrivalTime, delayedTime) {
  return (arrivalTime + delayedTime) % 24;
};

给定 arrivalTime（原到达时刻）和 delayedTime（延误小时数），返回列车在 24 小时制下的最终到达小时。

24 小时制本质是一个长度为 24 的环。时间相加后如果超过 23，就从 0 重新开始，所以直接对 24 取模即可。

- 先计算 arrivalTime + delayedTime。
- 对 24 取模完成回绕。
- 返回结果。

时间复杂度：O(1)。
空间复杂度：O(1)。

class Solution {
    public int findDelayedArrivalTime(int arrivalTime, int delayedTime) {
        return (arrivalTime + delayedTime) % 24;
    }
}

func findDelayedArrivalTime(arrivalTime int, delayedTime int) int {
    return (arrivalTime + delayedTime) % 24
}

class Solution {
public:
    int findDelayedArrivalTime(int arrivalTime, int delayedTime) {
        return (arrivalTime + delayedTime) % 24;
    }
};

class Solution:
    def findDelayedArrivalTime(self, arrivalTime: int, delayedTime: int) -> int:
        return (arrivalTime + delayedTime) % 24

var findDelayedArrivalTime = function(arrivalTime, delayedTime) {
  return (arrivalTime + delayedTime) % 24;
};