What is the time complexity of the optimal greedy algorithm for Partition Labels that uses a fixed-size array for last occurrences?

medium🪤 Complexity Trap Q5 of Q15

Greedy Algorithms - Partition Labels

AO(n) because it scans the string twice with constant-time operations

BO(1) since the array size is fixed

CO(n^2) because of nested loops checking character overlaps

DO(n * 26) due to scanning last occurrences for each character

Step-by-Step Solution

Solution:

Step 1: Analyze passes over input
The algorithm scans the string twice: once to record last occurrences, once to partition.
Step 2: Consider operations per character
Each operation is O(1) due to fixed-size array access; no nested loops.
Final Answer:
Option A -> Option A
Quick Check:
Two linear scans -> O(n) time complexity [OK]

Quick Trick: Two linear scans with constant-time ops -> O(n) [OK]

Common Mistakes:

MISTAKES

Trap Explanation:

PITFALL

Candidates often mistake the fixed alphabet size as a factor multiplying n, leading to O(n*26).

Interviewer Note:

CONTEXT

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