Available question text
Given a permutation of numbers 1..n, compute its lexicographic rank (index) among all permutations. The core challenge is counting how many permutations precede it efficiently using combinatorics (factorial number system / counting smaller unused elements) rather than generating all permutations.
Related questions
Continue with questions that share topics or the same question type.
Sources · 1 reference
These records explain where the question appears. A company tag or candidate report does not guarantee a future interview question.
Hello Interview · 1 record
No company association
Leetcode 3109. Find the Index of Permutation
Reported date not specified · 0 source reports
Source snapshot: Nov 12, 2026
View source