Count maximum path in string

Last updated: October 28, 2025

Quick Overview

Given a string consisting of lowercase letters, count the maximum number of distinct paths that can be formed by rearranging the characters in the string. A path is defined as a sequence of characters that can be traced without repeating any character. The function should return an integer representing the maximum number of such paths.

ServiceNow
Coding & Algorithms
Machine Learning Engineer
ServiceNow
October 28, 2025
Machine Learning Engineer
Technical Screen
Coding & Algorithms
Easy

10

13

3,278 solved


Given a string consisting of lowercase letters, count the maximum number of distinct paths that can be formed by rearranging the characters in the string. A path is defined as a sequence of characters that can be traced without repeating any character. The function should return an integer representing the maximum number of such paths.

ServiceNow uses this problem in the Technical Screen to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.

What the Interviewer Expects
  • Identify the correct data structure and algorithm for the problem
  • Write clean, bug-free code with proper variable naming
  • Analyze time and space complexity correctly
  • Handle basic edge cases (empty input, single element)
  • Communicate your thought process while coding
Key Topics to Cover
Time and space complexity analysis
Hash maps and frequency counting
Graph algorithms and traversal
Tree structures and recursion
Data structure selection and trade-offs
Sorting and searching
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
  • Can you solve this iteratively instead of recursively (or vice versa)?
  • How would you parallelize this solution?
  • What if the input doesn't fit in memory?
  • How would you modify your solution to handle streaming input?
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Sample Answer
Problem Analysis

To tackle the problem of counting the maximum number of distinct paths formed by rearranging a string's characters, we can recognize that each character can be used to form a distinct path only if it ...

Approach

The algorithm will follow these steps:

  1. Use a frequency counter (like a dictionary) to count occurrences of each character in the string.
  2. The maximum number of distinct paths that can be formed i...

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