Frontier AI Technical Interview Question Bank

Topic tags
Python
Algorithms

Reported interview periodNot available

Longest Substring Without Repeated Characters

Given a string, return the length of its longest contiguous substring containing no repeated character.

Practice focusThe empty string returns 0 . Treat characters as the language runtime's Unicode characters. Target O(n) time and O(k) space, where k is the number of distinct characters in the active input. Staged follow-ups 1. Return the substring or its half-open index range, not just its length. 2. Permit each character to appear at most m times. 3. Process a stream in chunks without retaining the entire prefix.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Merge Closed Intervals

Given a list of closed intervals [start, end], merge every overlapping pair and return the resulting non-overlapping intervals sorted by start position.

Practice focusAssume start <= end . Because intervals are closed, [1, 4] and [4, 6] overlap and become [1, 6] . The input may be unsorted and may contain duplicates. Staged follow-ups 1. Preserve associated metadata while merging. 2. Insert one interval into an already sorted, disjoint sequence. 3. Process intervals that arrive as a stream and discuss when output can be finalized.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Minimum Interval Removals

Given intervals [start, end], remove as few as possible so that the remaining intervals do not overlap. Intervals that only touch at an endpoint are compatible.

Practice focusAssume every interval satisfies start <= end . The input may be unsorted and may contain duplicates. Target O(n log n) time. Staged follow-ups 1. Return the retained or removed interval indices. 2. Assign positive weights and maximize retained weight rather than retained count. 3. Handle online arrivals and explain which guarantees can no longer be optimal.

Free practice

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Number of Islands

Given a rectangular grid of characters, where '1' is land and '0' is water, return the number of edge-connected land components. Diagonal cells are not connected.

Practice focusThe grid may be empty. You may either mutate the grid or maintain separate visited state, but state your choice. Target O(rows columns) time. Staged follow-ups 1. Return the area of the largest island. 2. Count islands as land cells are added incrementally. 3. Process a grid too large to hold fully in memory, one row at a time.

New public brief

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Binary Search

Given a strictly increasing array of integers and a target, return the target's index or -1 when it is absent.

Practice focusThe solution must run in O(log n) time and use O(1) auxiliary space. An empty array returns -1 . Staged follow-ups 1. Return the first position where the target could be inserted while preserving order. 2. Support duplicate values by returning the first matching index. 3. Search a conceptually unbounded sorted data source through a bounded-access interface.

Public brief

Topic tags
Python
Algorithms

ByteDanceCoding

Talk-through codingNo local grader

Reported interview periodNot available

Palindrome Integer

Determine whether a signed 32-bit integer reads identically from left to right and right to left in decimal notation.

Practice focusNegative numbers are not palindromes because of the sign. A positive number ending in zero is not a palindrome unless the value itself is zero. Staged follow-ups 1. Solve without converting the number to a string. 2. Reverse only half the digits to avoid overflow and unnecessary work. 3. Generalize the check to an arbitrary base from 2 through 36.

Public brief

Topic tags
Python
Algorithms

Coding exerciseCoding

Written response35 minutes

Reported interview periodN/A

Vial log

Return the vials that stayed inside a temperature range for their whole stay.

Practice focusScanning, Missing data through a written response exercise.

Public brief

Topic tags
Python
Algorithms

Coding exerciseCoding

Written response35 minutes

Reported interview periodN/A

Comment batches

Collapse consecutive comments on the same path into one batch.

Practice focusOrder, Grouping through a written response exercise.

Public brief

Topic tags
Python
Algorithms
Data structures

Coding exerciseCoding

Written response40 minutes

Reported interview periodN/A

Launch order

Return one valid order of steps, or report a cycle.

Practice focusOrdering, Cycles through a written response exercise.

Frontier AI technical interview question bank.

Frontier AI technical interview question bank.

Longest Substring Without Repeated Characters

Merge Closed Intervals

Minimum Interval Removals

Number of Islands

Binary Search

Palindrome Integer

Vial log

Comment batches

Launch order

Longest Substring Without Repeated Characters

Merge Closed Intervals

Minimum Interval Removals

Number of Islands

Binary Search

Palindrome Integer

Vial log

Comment batches

Launch order