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How to Solve The Number of the Smallest Unoccupied Chair Problem
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Start Free for WindowsMedium#1942
LeetCode ProblemThe Number of the Smallest Unoccupied Chair
There is a party where n friends numbered from 0 to n - 1 are attending. There is an infinite number of chairs in this party that are numbered from 0 to infinity. When a friend arrives at the party, they sit on the unoccupied chair with the smallest number. When a friend leaves the party, their chair becomes unoccupied at the moment they leave. If another friend arrives at that same moment, they can sit in that chair. You are given a 0-indexed 2D integer array times where times[i] = [arrivali, leavingi], indicating the arrival and leaving times of the ith friend respectively, and an integer targetFriend. All arrival times are distinct. Return the chair number that the friend numbered targetFriend will sit on.
ArrayHash TableHeap (Priority Queue)
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Problem Breakdown
Understanding the The Number of the Smallest Unoccupied Chair Problem
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Problem Statement
There is a party where n friends numbered from 0 to n - 1 are attending. There is an infinite number of chairs in this party that are numbered from 0 to infinity. When a friend arrives at the party, they sit on the unoccupied chair with the smallest number. When a friend leaves the party, their chair becomes unoccupied at the moment they leave. If another friend arrives at that same moment, they can sit in that chair. You are given a 0-indexed 2D integer array times where times[i] = [arrivali, leavingi], indicating the arrival and leaving times of the ith friend respectively, and an integer targetFriend. All arrival times are distinct. Return the chair number that the friend numbered targetFriend will sit on.
MediumProblem #1942
LeetCodeThe Number of the Smallest Unoccupied Chair
Related Topics
ArrayHash TableHeap (Priority Queue)
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Examples
# Example 1
Input
times = [[1,4],[2,3],[4,6]], targetFriend = 1
Output
1
# Example 2
Input
times = [[3,10],[1,5],[2,6]], targetFriend = 0
Output
2
Constraints
n == times.length
2 <= n <= 104
times[i].length == 2
1 <= arrivali < leavingi <= 105
0 <= targetFriend <= n - 1
Each arrivali time is distinct.
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Solve The Number of the Smallest Unoccupied Chair — There is a party where n friends numbered from 0 to n - 1 are attending. There i...
Here's the optimal approach using Array:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
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Frequently Asked Questions
Common questions about solving The Number of the Smallest Unoccupied Chair and using Phantom Code during coding interviews.
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Phantom Code catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
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The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
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