How hard is LeetCode 1914. Cyclically Rotating a Grid?

LeetCode 1914. Cyclically Rotating a Grid is rated Medium on LeetCode.

What topics does LeetCode 1914. Cyclically Rotating a Grid cover?

LeetCode 1914. Cyclically Rotating a Grid is tagged Array, Matrix and Simulation on LeetCode.

Cyclically Rotating a Grid — LeetCode 1914 Python Solution

MediumArrayMatrixSimulation

Problem: #1914
Pattern: Matrix and Grid
Reading time: 6 min
Source: leetcode.com

The problem

You are given an m x n integer matrix grid, where m and n are both even integers, and an integer k. The matrix is composed of several layers, which is shown in the below image, where each color is its own layer: A cyclic rotation of the matrix is done by cyclically rotating each layer in the matrix.

Example

Input: grid = [[40,10],[30,20]], k = 1
Output: [[10,20],[40,30]]
Explanation: The figures above represent the grid at every state.

Python solution

Python

class Solution:
    def rotateGrid(self, grid: List[List[int]], k: int) -> List[List[int]]:
        def rotate(p: int, k: int):
            nums = []
            for j in range(p, n - p - 1):
                nums.append(grid[p][j])
            for i in range(p, m - p - 1):
                nums.append(grid[i][n - p - 1])
            for j in range(n - p - 1, p, -1):
                nums.append(grid[m - p - 1][j])
            for i in range(m - p - 1, p, -1):
                nums.append(grid[i][p])
            k %= len(nums)
            if k == 0:
                return
            nums = nums[k:] + nums[:k]
            k = 0
            for j in range(p, n - p - 1):
                grid[p][j] = nums[k]
                k += 1
            for i in range(p, m - p - 1):
                grid[i][n - p - 1] = nums[k]
                k += 1
            for j in range(n - p - 1, p, -1):
                grid[m - p - 1][j] = nums[k]
                k += 1
            for i in range(m - p - 1, p, -1):
                grid[i][p] = nums[k]
                k += 1

        m, n = len(grid), len(grid[0])
        for p in range(min(m, n) >> 1):
            rotate(p, k)
        return grid

Complexity

Measure	Complexity
Time	O(m·n)
Space	O(1) to O(m·n) auxiliary

Pattern: Matrix and Grid

Treat a 2-D grid as a graph whose neighbours are the four adjacent cells. LeetCode 1914. Cyclically Rotating a Grid is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Matrix.

The matrix and grid guide has the Python template for the pattern and the 216 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 1914. Cyclically Rotating a Grid?: LeetCode 1914. Cyclically Rotating a Grid is rated Medium on LeetCode.
What topics does LeetCode 1914. Cyclically Rotating a Grid cover?: LeetCode 1914. Cyclically Rotating a Grid is tagged Array, Matrix and Simulation on LeetCode.