TypeScript Interview Programs

Return whether an ASCII string reads identically forwards and backwards; comparison is case-sensitive.

Easy· Two Pointers ·10 min

Given exactly two ASCII strings, return whether their case-sensitive character frequencies match.

Easy· Hashing ·10 min

Return n factorial for an integer n from 0 through 18.

Easy· Numbers ·10 min

Given exactly two integers, return their nonnegative greatest common divisor, with gcd(0,0) defined as 0.

Easy· Math ·10 min

The array contains distinct integers from 0 through n with exactly one missing, where n is its length. Return the missing integer.

Easy· Arrays ·10 min

Return the second distinct largest number, or null when fewer than two distinct numbers exist.

Easy· Arrays ·10 min

Return the first n Fibonacci numbers starting with 0 and 1, where 0 <= n <= 50.

Easy· Numbers ·10 min

Return all nonzero values in their original order followed by all zeroes.

Easy· Arrays ·10 min

Reverse the characters of an ASCII string, retaining spaces and punctuation.

Easy· Strings ·10 min

Given a strictly increasing array and a target, return its zero-based index or -1 when absent.

Easy· Sorting & Searching ·10 min

Return the sum of the decimal digits of the absolute value of an integer.

Easy· Numbers ·10 min

Return whether the integer is prime; values below 2 are not prime.

Easy· Math ·10 min

For each consecutive run of ASCII letters, output its character followed by its decimal count, including counts of one.

Medium· Strings ·25 min

Return the first ASCII character appearing exactly once, or the empty string if none exists.

Medium· Hashing ·25 min

Return the largest sum of a nonempty contiguous subarray. The input array has at least one element.

Medium· Dynamic Programming ·25 min

Return indices [i,j] with i < j and values summing to target. Choose the smallest j, then smallest i; return [] if absent.

Medium· Hashing ·25 min

Flatten a nested array of numbers into a numeric array in left-to-right depth-first order. Empty nested arrays contribute no elements.

Medium· Recursion ·25 min

Group records by category into objects {category,ids}. Preserve first-seen category order and input id order within each group, including duplicate ids.

Medium· Collections ·25 min

Given closed intervals [start,end] with start <= end, merge all overlaps including shared endpoints. Return intervals sorted by start.

Medium· Sorting & Searching ·25 min

Merge two nondecreasing arrays into one nondecreasing array, preserving duplicates.

Medium· Two Pointers ·25 min

Return unique primitive values in first-occurrence order; numeric 1 and string "1" are distinct. Implement a generic helper for strings and numbers.

Medium· Collections ·25 min

Rotate values right by nonnegative k positions, with k <= 1000000. An empty array remains empty.

Medium· Arrays ·25 min

Split values into consecutive chunks of positive size (1 to 10000). Only the final chunk may be shorter; use a generic chunk helper.

Medium· Collections ·25 min

Return the clockwise spiral traversal of a rectangular matrix, starting at its top-left cell. Empty matrices are allowed.

Medium· Matrices ·25 min

Return whether a string consisting only of parentheses, square brackets, and braces is properly nested.

Medium· Stack & Queue ·25 min

Return the units of rainwater trapped between nonnegative bar heights of unit width.

Hard· Two Pointers ·40 min

Given exactly two ASCII strings of length at most 500, return the minimum insertions, deletions, and substitutions needed to transform the first into the second.

Hard· Dynamic Programming ·40 min

For a nonempty array and 1 <= k <= its length, return the maximum of each consecutive window of length k.

Hard· Stack & Queue ·40 min

Return the maximum length of a contiguous substring with no repeated ASCII characters.

Hard· Sliding Window ·40 min

Return the median of two nondecreasing arrays whose combined length is positive. For an even total length, return the mean of the two middle values.

Hard· Sorting & Searching ·40 min