Leetcode #1560: Most Visited Sector in a Circular Track
In this guide, we solve Leetcode #1560 Most Visited Sector in a Circular Track in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
Given an integer n and an integer array rounds. We have a circular track which consists of n sectors labeled from 1 to n.
Quick Facts
- Difficulty: Easy
- Premium: No
- Tags: Array, Simulation
Intuition
The rules are explicit, so simulating the process step by step is safest.
Careful state updates prevent subtle bugs.
Approach
Translate the rules into state updates and apply them in order.
Track the final state or aggregate as required.
Steps:
- Translate rules into state updates.
- Iterate for each step.
- Return the final state.
Example
Input: n = 4, rounds = [1,3,1,2]
Output: [1,2]
Explanation: The marathon starts at sector 1. The order of the visited sectors is as follows:
1 --> 2 --> 3 (end of round 1) --> 4 --> 1 (end of round 2) --> 2 (end of round 3 and the marathon)
We can see that both sectors 1 and 2 are visited twice and they are the most visited sectors. Sectors 3 and 4 are visited only once.
Python Solution
class Solution:
def mostVisited(self, n: int, rounds: List[int]) -> List[int]:
if rounds[0] <= rounds[-1]:
return list(range(rounds[0], rounds[-1] + 1))
return list(range(1, rounds[-1] + 1)) + list(range(rounds[0], n + 1))
Complexity
The time complexity is , where is the number of sectors. The space complexity is .
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.