#grids

58 grids interview questions, asked at Google, Amazon, Meta and 13 more companies. Last asked Oct 2026.

Assign robots to their nearest pickup items on a grid with obstaclesCodingOn an m x n grid with obstacles there are k robots and k items. Send each robot to one item, preferring the item nearest to it by walking distance. Several robots can share the…
Last asked Oct 2026
+1
Number of islands as land is addedCodingA grid starts as all water. Positions are turned into land one at a time; after each addition, return the current number of islands (land cells connected up, down, left or right)…
Last asked Oct 2026
Fewest moves for a chess piece to capture the kingCodingA rectangular board has blocked squares, your piece and the opposing king. Your piece's type decides the directions it may step in, and it can never move onto a blocked square…
Last asked Oct 2026
Cell with the least total walking distance to all targets around wallsCodingA grid has targets, empty cells and walls. Walking moves up, down, left or right and cannot cross walls. Find a non-wall cell whose summed walking distance to every target is as…
Last asked Sep 2026
Sizes of connected regions in a binary image, in scan orderCodingA binary image is an m x n grid of 0s and 1s. Foreground pixels (1s) that touch up, down, left or right belong to the same region; diagonal neighbours do not. Return the size of…
Last asked Sep 2026
+4
Number of islandsCodingGiven a binary matrix, return how many islands it has: groups of 1 cells connected up, down, left or right (diagonals don't connect).
Last asked Sep 2026
Grid reachability for a robot that cannot reverseCodingA robot moves on a grid of open cells, blocked cells, a start S and a destination D. It always faces one of four directions, can never turn around, and may only turn in the ways…
Last asked Sep 2026
Grid path from start to target, then the path farthest from a catCodingAn N x N grid has a start cell S, a target cell T, water cells and land cells. You move one step up, down, left or right and can never enter water. 1. Decide whether you can get…
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
Sort a grid into snake order with adjacent swapsCodingAn n x n board holds each number from 1 to nn once. Rearrange it into snake order: the first row increases left to right, the second right to left, and so on, alternating. The…
Last asked Sep 2026
Shortest increasing path to a target value in a gridCodingGiven an integer grid, answer repeated queries. Each query names a target value; return the values along a shortest path from the top-left cell to a cell holding that value, where…
Last asked Sep 2026
Add one delivery center to minimize the worst distanceCodingA grid marks delivery centers with 1 and every other cell with 0. The distance between two cells is max(x1 - x2, y1 - y2) (moving in all eight directions). The grid's…
Last asked Sep 2026
Shortest path in a grid with obstacle eliminationCodingA grid has empty cells and obstacles. Find the fewest steps from the top-left to the bottom-right cell moving up, down, left or right, when you may remove up to k obstacles along…
Last asked Aug 2026
Time for grid signals to reach every target, then remove one blockerCodingA grid holds signal sources, targets and blockers. Signals spread from cell to neighboring cell, one step per unit of time, and cannot pass through blockers. 1. Return how long it…
Last asked Aug 2026
+1
Shortest distance from all buildingsCodingA grid has empty land, buildings and obstacles. Find the empty cell whose total walking distance to every building is smallest (moving up, down, left or right), or return -1 if no…
Last asked Aug 2026
Arrange crops into connected regions of a gardenCodingA rectangular garden has N rows and M columns, and there are K crop types. Crop i must take exactly counti cells, and the counts add up to N M. Return any planting that uses every…
Last asked Aug 2026
Collect the characters along a path in a gridCodingA 2D grid has one path that starts at (0, 0); path cells hold either or a letter, and other cells are empty. Follow the path and return the letters on it, in order, as a string…
Last asked Aug 2026
Longest straight run of one color in a gridCodingGiven a grid of colors such as R, G and B, return the length of the longest line of cells with the same color, running horizontally, vertically or diagonally.
Last asked Aug 2026
Robot route with charging cells: fewest charges, then battery, then movesCodingA robot crosses a grid from S to D. Cells are . (open), (blocked) or C (a charging cell). The battery limits how far the robot can go between charges, and a charging cell refills…
Last asked Aug 2026
Minesweeper: reveal a regionCodingImplement a click on a Minesweeper board. Clicking a mine ends the game. Clicking a cell with mines around it shows the count. Clicking a cell with none reveals it and spreads to…
Last asked Aug 2026
Is there an island of exactly size k?CodingGiven a grid of land and water, answer many queries of the form "is there an island of exactly k cells?". Find the islands once, then answer each query quickly, and discuss what…
Last asked Aug 2026
Count how many rectangles cover each grid cellCodingRectangles are laid on a grid, each one an update that covers a block of cells. Return, for every cell, how many rectangles cover it, without walking every cell of every…
Last asked Jul 2026
+1
Distance from every desk to its nearest bathroomCodingAn office floor plan is a grid of bathrooms, desks and open floor. For every desk, return how many steps (up, down, left, right) it takes to reach the closest bathroom. Expect…
Last asked Jul 2026
Shortest grid path with one cell conversionCodingFind the length of the shortest path across a grid when you are allowed to convert one blocked cell into an open one along the way.
Last asked Jun 2026
Shortest bridge between two islandsCodingA binary grid contains exactly two islands of 1s (4-directionally connected). Return the fewest 0 cells you must flip to 1 to connect them. Find one island with DFS, then expand…
Last asked Jun 2026
Find a repeating command program for a vehicle under fuel and memory limitsCodingA vehicle on a grid starts at a given cell with 100 fuel. Each move up, down, left or right costs one unit; at a station it can refuel 50 units; obstacles block movement. It can…
Last asked Jun 2026
Shortest path in a grid with blocked cellsCodingGiven a grid in which some cells are blocked, return the length of the shortest path from a start cell to a target cell, moving up, down, left or right, or report that no path…
Last asked Jun 2026
Fewest moves across a grid when each move can jump up to k cellsCodingOn a grid with blocked cells, each move goes up, down, left or right by one to k cells, without passing through a blocked cell. Return the fewest moves from the start to the…
Last asked Jun 2026
+1
Best meeting point on a gridCodingA grid marks several people's (or points') positions. Find the cell that minimizes the total distance to all of them. Start with a brute force (for example a BFS from each point)…
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
Blind maze escape: one command sequence for every startCodingA robot is somewhere in a grid maze of walls (), open cells (.) and an exit (E), but you do not know which open cell it starts on. It obeys the commands U, D, L and R, each moving…
Last asked Apr 2026
Count islands with diagonal connectivityCodingCount the islands in a grid of land and water where land cells are joined in all eight directions, diagonals included.
Last asked Apr 2026
+1
Minimum knight movesCodingOn a chess board (possibly infinite), return the fewest moves a knight needs to get from one square to another. Use BFS, and consider symmetry or bidirectional BFS to make it…
Last asked Apr 2026
+1
Max area of islandCodingGiven a binary matrix, return the area of the largest island: a group of 1 cells connected up, down, left or right (diagonals don't connect).
Last asked Mar 2026
Squirrel carrying nuts to a treeCodingA squirrel, a tree and several nuts are on a grid. The squirrel carries one nut at a time to the tree, moving one cell up, down, left or right per step. Return the fewest moves to…
Last asked Mar 2026
Rotting oranges: time for an infection to cover a gridCodingA grid has empty cells, healthy cells and infected cells. Every minute each infected cell infects its healthy neighbors up, down, left and right. Return the minutes until no…
Last asked Mar 2026
Nearest exit from a mazeCodingGiven a grid maze of walls and open cells and your starting cell, return the fewest steps to the nearest exit, an open cell on the border other than the start, or -1 if there is…
Last asked Feb 2026
Render, compress and invert a bitmap fontCodingA bitmap font is given as strings of 0 and 1 bits, one bitmap per character. 1. Render each character as a grid of text, with . for a 0 bit and another character for a 1 bit. 2…
Last asked Feb 2026
Time for a virus to infect the whole gridCodingA grid has infected, healthy and empty cells. Each minute the virus spreads from every infected cell to its healthy neighbours up, down, left and right. Return the number of…
Last asked Feb 2026
Trapping rain water IICodingGiven a 2D grid of cell heights, compute how much rainwater the grid holds after rain, with water able to run off the outer edge.
Last asked Feb 2026
Shortest path between two cells in a gridCodingGiven a grid with open and blocked cells, return the length of the shortest path from a start cell to a target cell moving up, down, left and right. A follow-up changes the…
Last asked Feb 2026
Place Tetris-like shapes in the first spot that fitsCodingYou have an n x m grid and a sequence of shapes from a small fixed set. Place the shapes one at a time, in order; each goes into the first position where it fits, scanning rows…
Last asked Feb 2026
Move instructions for a robot that cannot see the mazeCodingA robot is in a 2D maze but cannot see it. Produce the sequence of move instructions that gets it to the goal, under the rules the interviewer gives for what happens when a move…
Last asked Jan 2026
Flood fillCodingGiven an image as a grid of colors, a starting pixel and a new color, recolor the starting pixel and every pixel connected to it (up, down, left, right) that has the same original…
Last asked Jan 2026
Distance from every cell to the nearest taxiCodingA grid marks the cells where taxis are parked. Return, for every cell, the distance to the nearest taxi (moving up, down, left or right). Use a multi-source BFS and say why it…
Last asked Jan 2026
Walls and gatesCodingA grid holds walls, gates and empty rooms. Fill every empty room with the distance to its nearest gate, leaving rooms that cannot reach a gate untouched. Use one multi-source BFS…
Last asked Jan 2026
Making a large islandCodingIn a binary grid you may change at most one water cell to land. Return the size of the largest island you can end up with. Label each island and its size once, then try each water…
Last asked Dec 2025
Shortest path in a grid with obstaclesCodingGiven a 2D grid where some cells are blocked, find the length of the shortest path from the top-left cell to the bottom-right cell moving up, down, left or right, or return -1 if…
Last asked Dec 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
Find a target in an unknown grid with a robot APICodingA robot sits somewhere in a grid you cannot see: you don't know its size, its walls or where you start. You can only call the robot's API: move forward (which reports whether it…
Last asked Nov 2025
Cells water reaches flowing downhillCodingA 2D map gives the height of each cell. A drop of water lands on one cell and flows to neighbouring cells (up, down, left, right) whose height is not greater than the cell it is…
Last asked Oct 2025
One round of candy crush on a gridCodingAn integer matrix holds coloured blocks; equal numbers are the same colour and 0 is empty. Run one round: find every block that is part of a group to crush (clarify the rule; the…
Last asked Sep 2025
Place fixed shapes on a grid in orderCodingYou get an n x m grid and a list of shapes, like Tetris pieces that neither rotate nor fall. Place them in order: each goes at the first position, scanning from the top-left…
Last asked Sep 2025
Best locker location on a grid with obstaclesCodingOn a grid with obstacles, choose an empty cell for a locker so that the total walking distance to it from a set of given locations is as small as possible, walking around…
Last asked Aug 2025
Shortest path to collect all keysCodingA grid has walls, a start cell, keys (lowercase letters) and locks (the matching uppercase letters). A lock can only be passed once you hold its key. Return the fewest steps to…
Last asked Aug 2025
Rotting orangesCodingIn a grid, cells are empty, fresh fruit or rotten fruit. Each minute, fresh fruit next to rotten fruit (up, down, left, right) rots. Return the minutes until no fresh fruit is…
Last asked Jul 2025
Shortest bridgeCodingA grid holds exactly two islands. Return the fewest water cells to flip to connect them: mark one island with depth-first search, then expand from all its cells with breadth-first…
Last asked Jul 2025
Same-value region from a start pixel, and its borderCodingAn image is a grid of 0s and 1s. From a starting pixel, find every connected pixel with the same value. Follow-up: return the region's border, the neighbouring pixels that are not…
Last asked Jul 2025