Frontier AI Technical Interview Question Bank

Topic tags
Python
Data structures

Reported interview periodNot available

Maximum haul from non-adjacent houses

Each house on a street holds a known amount of money, and robbing two neighboring houses on the same night trips the alarm. Choose houses with no two adjacent to collect the largest possible total.

Practice focusRequirements - Line one is the house count. Line two lists that many non-negative integer amounts, separated by spaces. - Adjacency is positional, so choosing the house at index i rules out only i - 1 and i + 1 . - Return the best total as a decimal string with no separators. - A single house contributes its own amount, and a zero amount is a legal choice, so a street of zeros answers 0 . - Every house is a candidate; skipping a house is never required just because it is small. - run case passes case["stdin"] to solve .…

Free practice

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Next arrangement in lexicographic order

Rearrange an integer list into the next larger lexicographic arrangement, wrapping around to the smallest arrangement when no larger one exists.

Practice focusRequirements - Line 1 holds the length n . Line 2 holds n integers separated by spaces. - Compare arrangements position by position from the left. The next arrangement is the smallest arrangement strictly greater than the current one. - Duplicate values are allowed. - If the current arrangement is already the largest, return the smallest arrangement, with values in ascending order. - Print the resulting list in one space-separated line, keeping the same length and the same multiset of values. - run case(case: dict) forwards case["stdin"] to solve .…

Free practice

Topic tags
Python
Data structures
Product design

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNot available

Dot product of two long integer vectors

Read a shared length and two integer vectors of that length, then return their dot product as a decimal string. Most entries are zero, so the useful work should follow the non-zero positions rather than the dec…

Practice focusRequirements - Line 1 is the length n ; line 2 holds n integers for the first vector; line 3 holds n integers for the second. - Some inputs carry the two characters backslash and n instead of real line breaks; treat both forms as line separators before parsing. - Multiply matching positions, then add the products. Entries may be negative, so the sum can be negative or zero. - Return the total as a plain decimal string with no padding, no plus sign, and no newline. - Do not print the individual products or the operand vectors.…

New public brief

Topic tags
Python
Algorithms
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodJan 2026–Aug 2026

Sum the in-range values of a search tree

Add up every node value that falls inside a closed interval in a binary search tree supplied as a level-order sequence.

Practice focusRequirements - Line 1 lists the tree in level order, comma separated, with null marking a missing child. - Line 2 holds low,high , both endpoints included. - Return the sum of all node values v with low <= v <= high as a decimal string. - Return "0" when the first token is null or when no value lies in the range. - The listing describes a valid binary search tree. - run case(case: dict) forwards case["stdin"] to solve . - Do not append a trailing newline to the returned string; return the value exactly once.

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Ancestor lookup with upward-only links

Every node in a tree stores only the id of its parent. Given two node ids, find their deepest shared ancestor using those upward links alone.

Practice focusRequirements - Line one is the node count n . Line two gives n parent ids in node order: the value at position i is the parent of node i , and a root is marked -1 . - Line three holds the two query ids separated by whitespace. - Node identity is the array position, so ids run from 0 to n - 1 . - A node counts as an ancestor of itself, so querying a node against one of its descendants returns that node. - Return the id of the deepest common ancestor as a decimal string, or -1 when the two nodes belong to different trees.…

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Aug 2026

Shared ancestor of two nodes in a binary tree

A binary tree arrives in level-order form along with two node values. Identify the lowest node whose subtree contains both values.

Practice focusRequirements - Line one is the level-order values separated by commas; null marks a missing child and the line may be wrapped in [...] . - Line two holds the two target values separated by a comma. - Node values are unique, and both targets appear in the tree. - A node counts as its own descendant, so a parent and child query answers the parent. - Return the value of the lowest shared ancestor as a decimal string, not its position in the serialization. - When one candidate ancestor lies below another, report the deeper one.…

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodDec 2025–Jul 2026

Column order of a binary tree

Rebuild a binary tree from its level-order serialization, then group the node values by column, moving left to right across columns. Inside one column the values should follow the order in which a breadth-first…

Practice focusRequirements - The first line is a level-order serialization separated by commas. A missing child is written as null , and the whole line may optionally be wrapped in square brackets. An empty line or [] means there is no tree. - Children attach in queue order: each non-null node consumes the next two slots as its left child and then its right child. - The root sits in column 0; a left edge shifts the column by -1 and a right edge by +1 . - Emit one inner list per occupied column, ordered from the smallest column offset to the largest.…

Public brief

Topic tags
Python
Data structures

MetaCoding

Python codingWebAssembly + public tests

Reported interview periodNov 2025–May 2026

Kth largest value with duplicates counted

Return the k-th value in descending order from an integer array, treating equal values as separate entries. The input arrives in one of two line layouts.

Practice focusRequirements - Layout A: line one is the element count, line two holds the integers, and line three is k . - Layout B: line one is nums=[3,2,1,5,6,4] and line two is k=2 , with no space before either equals sign. - k is one-based and always lies between 1 and the array length, so k = 1 asks for the maximum and k equal to the length asks for the minimum. - Return the selected value as a decimal string; it is a value, not a position.…

Public brief

Topic tags
Python
Data structures

Coding exerciseCoding

Written response35 minutes

Reported interview periodN/A

Grade book

An in-memory grade book with a ranking that does not treat a missing score as zero.

Practice focusState, Ranking, Edge cases 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.

Maximum haul from non-adjacent houses

Next arrangement in lexicographic order

Dot product of two long integer vectors

Sum the in-range values of a search tree

Ancestor lookup with upward-only links

Shared ancestor of two nodes in a binary tree

Column order of a binary tree

Kth largest value with duplicates counted

Grade book

Launch order

Maximum haul from non-adjacent houses

Next arrangement in lexicographic order

Dot product of two long integer vectors

Sum the in-range values of a search tree

Ancestor lookup with upward-only links

Shared ancestor of two nodes in a binary tree

Column order of a binary tree

Kth largest value with duplicates counted

Grade book

Launch order