Coding interview problems

Find the indices of two distinct values whose sum matches a target.

Sort and merge every overlapping or touching interval into a disjoint list.

Return a string with every character in reverse order without changing characters.

Find the longest leading substring shared by every string in a list.

Determine whether a phrase reads the same after ignoring case and non-alphanumeric characters.

Count every contiguous substring that reads the same forward and backward.

Return the longest contiguous substring that is a palindrome.

Check whether the values represented by a singly linked list form a palindrome.

Convert a valid canonical Roman numeral into its integer value.

Generate every letter combination represented by digits on a telephone keypad.

Validate that every bracket closes in the correct order and with the matching type.

Return the starting index of the first exact occurrence of one string inside another.

Measure the final whitespace-delimited word in a string.

Generate an n-by-n matrix filled clockwise in spiral order.

Produce the classic FizzBuzz sequence using divisibility rules.

Determine whether any integer appears more than once in an array.

Return the largest sum obtainable from a non-empty contiguous subarray.

Compute the zero-indexed Fibonacci number with an iterative recurrence.

Compute the product of all positive integers up to a non-negative input.

Move every zero to the end while preserving non-zero element order.

Find the only value that is not paired using constant extra space.

Find the best profit from one buy followed by one later sale.

Check whether two lowercase strings contain identical character frequencies.

Locate a target in a sorted unique array using logarithmic search.

Count ASCII vowels in a string without changing other characters.

Count ordered one-step and two-step paths to the top of a staircase.

Build prefix and suffix products without division.

Compute water trapped between elevation bars after rainfall.

Measure the minimum insertions, deletions, and replacements between two strings.

Find the combined median without fully merging two sorted arrays.

Measure the longest contiguous substring of balanced parentheses.

Determine whether a base-10 integer reads identically in reverse.

Add one to a number represented as an array of digits.

Find the element that appears more than half the time in an array.

Check whether one string is a subsequence of another.

Find the index of the first non-repeating character in a string.

Return the index where a target should be inserted into a sorted array.

Maximize the loot from non-adjacent houses along a street.

Decide whether you can reach the last index of an array of jump lengths.

Find the fewest coins needed to make up a given amount.

Find the length of the longest substring without repeating characters.

Find two lines that together with the x-axis hold the most water.

Count the number of islands in a grid of land and water cells.

Determine whether a string can be segmented into words from a dictionary.

Find the length of the longest strictly increasing subsequence.

Find the area of the largest rectangle that fits under a histogram.

Return the maximum of every contiguous window of size k.

Find the minimum number of jumps needed to reach the last index.

Reverse a singly linked list in place using real ListNode structures.

Find the maximum depth of a binary tree using real TreeNode structures.

Determine whether all courses can be completed given prerequisite pairs.

Find how many minutes are needed for rot to spread to every fresh orange.

Find the edge that creates a cycle in an otherwise tree-shaped graph.

Return the kth largest value without requiring a fully sorted array.

Return the k values that occur most often in an integer array.

Generate every subset in the power set of a distinct integer array.

Swap every binary-tree node's left and right children.

Determine whether two binary trees have identical structure and values.

Check whether a binary tree satisfies strict BST ordering.

Return binary-tree values grouped by breadth-first level.

Find the lowest shared ancestor of two values in a binary search tree.

Merge two sorted linked lists by rewiring their nodes.

Detect a cycle from a linked list represented by next-node indices.

Reorder a linked list by alternating nodes from its front and back.

Deep-copy a connected graph from its adjacency-list representation.

Find grid cells that can flow to both oceans under height constraints.

Compute how long a weighted directed network takes to receive a signal.

Merge k sorted sequences using a heap of current candidates.

Return the median after incrementally inserting every stream value.

Generate every ordering of a distinct integer array.

Find target-sum combinations when candidate values may be reused.

Find a word by backtracking through adjacent grid cells.

Execute insert, exact-search, and prefix-search operations on a trie.

Build a trie that supports exact letters and wildcard searches.

Simulate a bounded least-recently-used key-value cache.