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Grokking the Coding Interview Patterns in Python

Spiral Matrix

Explore how to return matrix elements in spiral order by mastering traversal techniques and logical problem structuring. This lesson helps you understand matrix operations essential for coding interviews and build efficient solutions.

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Statement

Given an m×nm\times n matrix, return an array containing the matrix elements in spiral order, starting from the top-left cell.

Constraints:

  • 1≤1\leq matrix.length ≤10\leq 10
  • 1≤1\leq matrix[i].length ≤10\leq 10
  • −100≤-100\leq matrix[i][j] ≤100\leq 100

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Spiral Matrix

1.

What is the output if the following matrix is given as input?

matrix = [[2, 6, 8],
                  [3, 4, 8],
                  [9, 8, 8]]

A.

[2, 6, 8, 3, 4, 8, 9, 8, 8]

B.

[2, 6, 8, 8, 8, 8, 9, 3, 4]

C.

[2, 6, 8, 8, 4, 3, 9, 8, 8]

D.

[8, 6, 2, 3, 9, 8, 8, 8, 4]

1 / 3

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
1
2
3
4
5
6

Try it yourself

Implement your solution in the following coding playground:

Python
usercode > main.py
def spiral_order(matrix):



  # Replace this placeholder return statement with your code

  return [-1]
Spiral Matrix