#StackBounty: #python #interview-questions Clockwise spiral traversal of 2D input matrix

Bounty: 50

I found this interview question online at Pramp:

Given a 2D array (matrix) inputMatrix of integers, create a function spiralCopy that copies inputMatrix’s values into a 1D array in a spiral order, clockwise. Your function then should return that array. Analyze the time and space complexities of your solution.

Example:

inputMatrix = [
    [1, 2, 3, 4, 5],
    [6, 7, 8, 9, 10],
    [11, 12, 13, 14, 15],
    [16, 17, 18, 19, 20]
]

output:

[1, 2, 3, 4, 5, 10, 15, 20, 19, 18, 17, 16, 11, 6, 7, 8, 9, 14, 13, 12] 

Constraints:

  • 1 ≤ inputMatrix[0].length ≤ 100
  • 1 ≤ inputMatrix.length ≤ 100

My solution

def spiral_copy(inputMatrix):
    output = []

    top_row = 0
    bottom_row = len(inputMatrix) - 1
    left_col = 0
    right_col = len(inputMatrix[0]) - 1

    while top_row <= bottom_row and left_col <= right_col:

        for i in range(left_col, right_col + 1):
            output.append(inputMatrix[top_row][i])
        top_row += 1

        for i in range(top_row, bottom_row + 1):
            output.append(inputMatrix[i][right_col])
        right_col -= 1

        if top_row > bottom_row: break

        for i in range(right_col, left_col - 1, -1):
            output.append(inputMatrix[bottom_row][i])
        bottom_row -= 1 

        if left_col > right_col: break

        for i in range(bottom_row, top_row - 1, -1):
            output.append(inputMatrix[i][left_col])
        left_col += 1  

    return output

Passed these Test cases:

Input   
[[1,2],[3,4]]
Expected Result
[1, 2, 4, 3]
Input
[[1,2],[3,4]
Expected Result
[1, 2, 4, 3]

Input
[[1,2,3,4],[5,6,7,8],[9,10,11,12]]
Expected Result
[1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7]

input
[[1,2],[3,4]
Expected Result
[1, 2, 3, 4, 5, 6, 12, 18, 17, 16, 15, 14, 13, 7, 8, 9, 10, 11]

Input
[[1,0],[0,1]]
Expected Result
[1, 0, 1, 0]

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


Get this bounty!!!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.