Is Shift 2D Grid easy or hard?

Shift 2D Grid is classified as an Easy problem on LeetCode with an acceptance rate around 68%. The main challenge is recognizing that the matrix can be treated as a circular array to avoid repeated simulation.

How to solve Shift 2D Grid in O(n)?

Flatten the m x n grid into a conceptual 1D array of length m*n. For each element, compute its new index after k shifts using modular arithmetic: (index + k) % (m*n). Convert the resulting index back to row and column positions to rebuild the grid in O(mn) time.

What is the best approach for Shift 2D Grid?

The most efficient approach treats the grid as a circular 1D array. Convert each cell (row, col) into a linear index, shift it using (index + k) % (m * n), and map it back to 2D coordinates. This completes the transformation in O(mn) time with O(mn) extra space and avoids repeatedly simulating shifts.

What data structure is used in Shift 2D Grid?

The problem primarily uses arrays and matrices. The optimal solution relies on index arithmetic to treat the matrix as a circular array, while the simulation approach updates elements directly inside the matrix.

What is the time complexity of Shift 2D Grid?

The optimal solution runs in O(mn) time where m and n are the grid dimensions. Each element is processed once to compute its final position after k shifts. A direct simulation approach takes O(kmn) time because the entire grid is shifted k times.

Shift 2D Grid Python or Java solution approach?

Both Python and Java implementations typically use the index‑mapping technique. Iterate through the grid, compute the flattened index, shift it using modulo arithmetic, and place the value in the computed row and column of the result grid.

Is Shift 2D Grid asked at Google, Amazon, or Meta?

Shift 2D Grid is a common entry‑level matrix manipulation problem used in coding interviews and practice sets. Variations of grid rotation, circular array shifts, and matrix index mapping appear in interviews at companies like Amazon and Google.

Description Hints 2 Solution Video 10:18

1260. Shift 2D Grid

Easy74.3% acceptance1 company

Given a 2D grid of size m x n and an integer k. You need to shift the grid k times.

In one shift operation:

Element at grid[i][j] moves to grid[i][j + 1].
Element at grid[i][n - 1] moves to grid[i + 1][0].
Element at grid[m - 1][n - 1] moves to grid[0][0].

Return the 2D grid after applying shift operation k times.

Example 1:

Input: grid = [[1,2,3],[4,5,6],[7,8,9]], k = 1
Output: [[9,1,2],[3,4,5],[6,7,8]]

Example 2:

Input: grid = [[3,8,1,9],[19,7,2,5],[4,6,11,10],[12,0,21,13]], k = 4
Output: [[12,0,21,13],[3,8,1,9],[19,7,2,5],[4,6,11,10]]

Example 3:

Input: grid = [[1,2,3],[4,5,6],[7,8,9]], k = 9
Output: [[1,2,3],[4,5,6],[7,8,9]]

Constraints:

m == grid.length
n == grid[i].length
1 <= m <= 50
1 <= n <= 50
-1000 <= grid[i][j] <= 1000
0 <= k <= 100

Asked at 1 company

Amazon

Topics

Hints open one at a time

Hint 1

Simulate step by step. move grid[i][j] to grid[i][j+1]. handle last column of the grid.

Hint 2

Put the matrix row by row to a vector. take k % vector.length and move last k of the vector to the beginning. put the vector to the matrix back the same way.

10:18

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution

LanguageLoading editor…

1class Solution:
2    def shiftGrid(self, grid: List[List[int]], k: int) -> List[List[int]]:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2Case 3

Input

[[1,2,3],[4,5,6],[7,8,9]]
1

Input

[[3,8,1,9],[19,7,2,5],[4,6,11,10],[12,0,21,13]]
4

Input

[[1,2,3],[4,5,6],[7,8,9]]
9

Your code is saved on this device.Solution