Limit tree height by deleting nodesCodingYou are given a rooted N-ary tree. Every node has a unique integer id. The tree is passed as children: dictint, listint (a node with no entry has no children) together with the…
Last asked Oct 2026
#dynamic programming
Minimum time to finish dependent steps run in parallelCodingA job is split into n steps numbered 0 to n - 1; step i takes durationsi minutes. A pair u, v in dependencies means step u must finish before step v starts. Any number of steps…Last asked Oct 2026
Paint house: cheapest daily colors with no repeat on consecutive daysCodingFor the next n days a store sells blue, green and red shirts, and you get three cost arrays, one per color, giving each color's price on each day. You buy exactly one shirt every…Last asked Oct 2026- Concatenated wordsCodingGiven a list of distinct words, return every word that can be split into two or more pieces that are each a word in the list (the same word may be used more than once). A shorter…Last asked Oct 2026
+1Weighted job schedulingCodingEach job has a start time, an end time and a profit. Choose jobs that do not overlap to make the most profit. Sort jobs by end time; for each job, binary search for the last job…Last asked Sep 2026
Count grid paths through ordered checkpointsCodingAn n x m grid. A path starts at the bottom-left cell and ends at the bottom-right cell. Each move goes one column to the right and either one row up, the same row, or one row…Last asked Sep 2026- Ones and zeroesCodingGiven a list of binary strings and two budgets, at most maxzeros zeros and at most maxones ones in total, choose as many strings as possible so that the chosen strings together…Last asked Sep 2026
Minimum-cost encryption of a directory treeCodingA storage service keeps a filesystem as a tree: Compliance requires every file in the tree to end up encrypted. You can issue two kinds of calls: - encrypt(filepath)Last asked Sep 2026- +2Insert plus, times and parentheses to reach a targetCodingYou are given an equation whose left side is a sequence of non-negative integers with no operators between them, and whose right side is a target. For example: 2 3 4 = 20. Insert…Last asked Sep 2026
Predict the winner of a pick-from-either-end gameCodingTwo players take turns removing a number from either end of an array and adding it to their score; player 1 moves first and both play optimally. Return whether player 1 can win (a…Last asked Sep 2026
House robber IV: smallest possible maximum over k non-adjacent picksCodingA row of houses (or servers) each holds a value. Choose at least k of them with no two next to each other. Among all valid choices, make the largest chosen value as small as…Last asked Sep 2026
Paint houseCodingFor n days you buy one shirt a day in blue, green or red, and each color's price changes by day. You may not buy the same color two days in a row. Return the lowest total cost.Last asked Sep 2026- Longest non-decreasing subarray after changing one elementCoding1. Warm-up: return the length of the longest run of consecutive elements that is strictly increasing. 2. Given an integer array, return the longest contiguous non-decreasing…Last asked Aug 2026
+2Word breakCodingReturn whether a string can be split into a sequence of words from a dictionary, where words may be reused. Give the dynamic programming solution and its cost.Last asked Aug 2026- Maximum subarray sum of an array repeated k timesCodingWrite an integer array out k times back to back and return the largest sum of a non-empty contiguous subarray of the result. Do it without building the repeated array, and explain…Last asked Aug 2026
- Delete and earnCodingTaking a value x from the array earns x points but deletes every x - 1 and x + 1. Return the most points you can earn. Explain how this reduces to the house robber recurrence over…Last asked Aug 2026
- Choose words with no shared letters to cover the most lettersCodingGiven a list of lowercase words, pick a subset in which no letter appears twice across the chosen words, maximizing the number of distinct letters covered. Start with a correct…Last asked Aug 2026
- Valid palindrome after deleting at most k charactersCodingReturn whether a string can become a palindrome by deleting at most k characters. Relate it to the longest palindromic subsequence and give the time and space of your solution.Last asked Aug 2026
- Count non-decreasing arrays with given digit sumsCodingYou get an array requiredSum of length n. Count arrays result of length n that are non-decreasing and where the digit sum of resulti equals requiredSumi for every i, within the…Last asked Aug 2026
Two contiguous delivery routes with the most revenueCodingStops along a line each bring some revenue. Pick two contiguous routes (segments of stops) that do not overlap so that their total revenue is as large as possible.Last asked Jul 2026- Edit distanceCodingReturn the fewest single-character insertions, deletions and replacements that turn one string into another.Last asked Jul 2026
- Max-score grid descent with limited two-row jumpsCodingYou are given an N x M grid of integers board. Rows and columns are numbered from 0, and a cell's value is the score you collect when you visit it. Values may be negative. A path…Last asked Jul 2026
+1Subset sum to a targetCodingGiven a list of positive integers nums and a non-negative integer target, decide whether some subset of nums adds up to exactly target. Each element may be used at most once…Last asked Jul 2026- Best time to buy and sell stock, every variantCodingGiven daily stock prices, solve the variants of the maximum-profit problem (for example a single trade, many trades, or at most k trades) with one unified approach.Last asked Jul 2026
- Regular expression matchingCodingDecide whether a whole string matches a pattern where . matches any single character and matches zero or more of the element before it.Last asked Jul 2026
Decode waysCodingLetters are encoded as numbers, A = 1 through Z = 26. Given a string of digits, count how many ways it can be decoded back into letters. Handle zeros carefully and solve it with…Last asked Jun 2026- Fill a layover with the fewest bookingsCodingYou land with a long layover and want to spend all of it on bookable local experiences. Each experience has a fixed whole-number duration in hours, and you may book the same…Last asked Jun 2026
- Fewest bills and coins to make changeCodingGiven an amount and the denominations of the bills and coins available, return the fewest pieces that add up to the amount.Last asked Jun 2026
- Boolean expression tree with leaf flipsCodingA tree's leaves hold true or false and its inner nodes are boolean operators. Evaluate the tree, then find the fewest leaf flips that make the root come out to a wanted value.Last asked Jun 2026
- Max-score jumps with primes ending in 3CodingYou are given a non-empty integer array nums of length n. You stand on index 0 and must finish on index n - 1. From index i you may move forward in one of two ways: - Step: move…Last asked Jun 2026
- Group booking across properties in one neighborhoodCodingA rental company houses groups in its properties. A group may be split across several properties, but all of them must be in the neighborhood the group asked for. Implement…Last asked May 2026
- Build a target string from the fewest substrings of a sourceCodingExpress a target string as a concatenation of substrings of a source string, each given by its index range, using as few pieces as possible. Follow-up: after one character of the…Last asked May 2026
- Longest water-flow path with momentumCodingYou get an m x n matrix of heights. Water starts at any cell and moves to a neighboring cell up, down, left or right. Whether it may move on depends on the heights and on the…Last asked Apr 2026
- Count ways to spell a word with element symbolsCodingGiven the symbols of the chemical elements and a word, count the ways to write the word as a sequence of element symbols, ignoring case. For example, "Physics" splits as…Last asked Apr 2026
GPU clusters: capacity left per day and the best K-switch planCodingYou run a few GPU clusters with fixed daily capacities, for example 10, 20. Each day a list of usage records takes GPUs from clusters (a record names the day, the cluster and how…Last asked Apr 2026
Factory network cost with stage-to-stage transportCodingA company is planning a chain of factories. Each factory has several candidate options, and you must pick exactly one option for every factory. The interview comes in parts; each…Last asked Apr 2026- +1Largest all-ones square and rectangle in a binary matrixCodingGiven a grid of 0s and 1s, return the area of the largest square made only of 1s. Then extend your approach to the largest all-ones rectangle.Last asked Apr 2026
- Best time to buy and sell stockCodingGiven daily prices, return the most profit you can make. First allow any number of buy-then-sell transactions (holding one share at a time), then allow only one transaction.Last asked Apr 2026
- Best-scoring ski run through a trail mapCodingA ski area has mapped its one-way trails between named checkpoints. The trail map has no cycles: once you ski down a trail you can never get back to where you were. Every trail…Last asked Mar 2026
- Russian doll envelopesCodingEach envelope has a width and a height. One fits inside another when both its width and height are strictly smaller. Return the largest number of envelopes you can nest one inside…Last asked Mar 2026
Score how close a string is to a palindromeCodingDesign a score for strings that are almost palindromes and implement it. Decide what the score measures (for example, mismatched pairs when comparing from both ends, or the fewest…Last asked Mar 2026- Probability of landing in a range on a dice walkCodingYou start at position 0 on an endless line. Each turn you roll a die with faces 1 to K and move forward that many steps. You win if you finish inside the range mn, mx, and lose…Last asked Mar 2026
- Fewest coins when change can be given backCodingYou need to pay an amount using coins of given denominations, but you may overpay and receive change back in the same denominations. Return the fewest coins that change hands in…Last asked Mar 2026
- Shortest run-length encoding after deleting k charactersCodingRun-length encoding writes each run of a repeated character as the character followed by the run length when the run is longer than one, so "aaabcc" becomes "a3bc2". Given a…Last asked Feb 2026
- +1Cheapest flights within K stopsCodingGiven flights as (from, to, price), a source, a destination and an integer k, return the cheapest price from the source to the destination using at most k stops, or -1 if there is…Last asked Feb 2026
- Best time to buy and sell stock: one trade, then twoCodingGiven a stock's daily prices, return the most profit you can make: 1. With one buy and one later sell. 2. With at most two non-overlapping trades.Last asked Feb 2026
- Sum of distances from every node in a treeCodingGiven an undirected tree with n nodes, return for every node the sum of its distances to all other nodes. A BFS from every node is too slow; compute it in linear time with two…Last asked Jan 2026
- +3Maximum sum of non-adjacent houses, on a line, a circle and a treeCodingEach house holds some value and you cannot take two neighbours. Find the best total for houses in a row, then for houses arranged in a circle, then for houses arranged as a binary…Last asked Jan 2026
- Best-matching binary pattern with wildcardsCodingYou get a list of patterns over 0, 1 and a wildcard that matches either bit, and a query string of bits. Return the pattern that matches the query best. Agree on what "best" means…Last asked Jan 2026
Bridge and torch problemCodingPeople must cross a bridge at night with one flashlight. At most two cross at once, a pair moves at the slower person's speed, and someone has to bring the flashlight back. Given…Last asked Jan 2026- Fewest conflicts when merging branchesCodingSeveral branches have to be merged, and the order of the merges changes how many commit conflicts come up. Given the branches and how conflicts arise between them, return the…Last asked Jan 2026
- Most deliveries on a line within a distance limitCodingDelivery points lie on a number line and the courier may travel at most a given distance. Choose deliveries to complete as many as possible, and among the best choices, minimise…Last asked Dec 2025
- Longest palindromic subsequenceCodingReturn the length of the longest subsequence of a string that reads the same forwards and backwards. Give the interval dynamic programming and its O(n^2) time.Last asked Dec 2025
- Minimum time to finish target courses in a prerequisite DAGCodingCourses form a directed acyclic graph of prerequisites and each course takes a given time; any number of courses can run at once as soon as their prerequisites are done. Return…Last asked Dec 2025
- Longest palindromic substringCodingReturn the longest substring of a string that reads the same forwards and backwards. Start with expanding around each center, state the time and space, and say how you would get…Last asked Nov 2025
- Count single-colour squares in a character gridCodingEach cell of a grid holds a character standing for a colour. Count all square sub-grids whose cells all have the same colour, of every size. Use the DP where each cell stores the…Last asked Nov 2025
- Max profit when taking a value skips aheadCodingYou walk an array of positive integers from index 0. At index i you either take arri and jump to index i + 1 + arri, or skip it and move to i + 1. Return the largest total you can…Last asked Oct 2025
- Trapping rain waterCodingGiven bar heights in an elevation map, each of width 1, compute how much water is trapped after rain. Start with the brute-force solution and its complexity, then improve it to…Last asked Sep 2025
- From 0/1 knapsack to bounded knapsackCodingStart with the 0/1 knapsack: items with weights and values, a capacity, and each item used at most once; return the best total value. Then each item may be used up to a given…Last asked Sep 2025
- Longest common contiguous subarrayCodingGiven two integer arrays, return the length of the longest run of values that appears contiguously in both. Start with dynamic programming, then discuss reducing the memory or…Last asked Sep 2025
Sum of products over all subarraysCodingAn online assessment with two problems. 1. A simplified text justification: lay words out into lines of a fixed width. 2. Given an array, return the sum, over every contiguous…Last asked Aug 2025- Target sumCodingPut a + or - in front of every number in an array and count how many ways the expression adds up to a target. Write the recursive solution, then turn it into a dynamic program…Last asked Aug 2025
- Valid palindrome IIICodingReturn whether a string can become a palindrome by deleting at most k characters. Relate it to the longest palindromic subsequence and solve it with dynamic programming.Last asked Aug 2025
- Longest increasing subarray and subsequenceCodingTwo warm-ups on one array: 1. The longest strictly increasing contiguous run (for 1, 2, 1, 2, 3 it is 1, 2, 3). 2. The longest increasing subsequence, whose elements need not be…Last asked Jul 2025
- Fewest flips to split a binary string into even uniform blocksCodingA string of 0s and 1s must be cut into blocks of even length where each block is all 0s or all 1s. Find the fewest bit flips that make this possible, and among those, the fewest…Last asked Jul 2025
- Longest subsequence with at most k value changesCodingYou get an integer array elements and a non-negative integer k. Choose a subsequence of elements: delete any number of items (possibly none) and keep the rest in their original…
- Reachable sum with reusable values and a huge targetCodingGiven a non-empty list nums of positive integers and a target k, return true if some multiset of values from nums sums to exactly k, and false otherwise. You may use each value…
- Regex matcher with starred groupsCodingImplement a small regex engine for a text-processing pipeline. Write ismatch(s: str, pattern: str) - bool. It returns True only when the whole string s matches pattern. The…
- Split parcels into the most balanced shipmentsCodingParcels sit on a conveyor in a fixed order, and weightsi is the weight of the i-th parcel. You must cut the line into contiguous shipments so that every parcel belongs to exactly…
- Maximum path sum between two leaves of a binary treeCodingYou are given the root of a binary tree. Every node stores an integer, which may be negative. A leaf is a node with no children. A leaf-to-leaf path starts at one leaf, moves…
- Max flight distance with limited energyCodingYou are planning a trip over n days. disti is how far you can fly on day i (a non-negative integer). You start with k units of energy, and k is also the most energy you can hold…
- Longest subsequence of one string that is a substring of anotherCodingGiven two strings x and y, return the length of the longest string t such that: - t is a subsequence of x: its characters appear in x in the same order, but not necessarily next…
- +1Multi-tap keypad: every string a press sequence can spellCodingAn old phone types letters by multi-tap: pressing a key once gives its first letter, twice in a row gives its second letter, and so on. Use this keypad: Key Letters ------ 1 A B C…
- Type a word on a grid keyboard with a jump limitCodingYou are typing a word with one finger on an unusual keyboard: an m x n grid of characters. Moving the finger from cell (r1, c1) to cell (r2, c2) covers a Manhattan distance of r1…
- Longest path in a DAG from an edge listCodingYou are given a directed acyclic graph as a list of edges. Each edge is a pair u, v of node names and means there is an edge from u to v. A node exists only if it appears in at…
- Count colorings of a row of houses with fixed end colorsCodingA contractor is repainting a row of n houses, numbered 0 to n - 1. There are k paint colors, numbered 0 to k - 1. The new paint job must follow two rules: - Two neighboring houses…
- Ball picking game: take one or two from the frontCodingBalls stand in a single line. Each ball has an integer value, which may be positive, zero, or negative. Two players take turns, and player 1 moves first. Both start with a score…
Distinct OR values of increasing subsequencesCodingGiven an integer array arr, define the goodness of a sequence as the bitwise OR of all its elements. The goodness of the empty sequence is 0. A subsequence keeps elements in their…