Draw a Line on a Board | Dataford Interview Questions

Paint a board: given a matrix whose cells all start as 'O', draw a line from (x0, y0) to (x1, y1), marking the cells the line passes through. A perfect diagonal such as (0,0) to (3,3) is straightforward, but you must also handle a non-45-degree line such as (0,0) to (4,7). Asked in the onsite coding round 2 stage. The author warns this interviewer was a former Microsoft imaging engineer and reuses this question.

Implement draw_line(board, x0, y0, x1, y1). Coordinates use board[y][x]; mutate and return the board, replacing every rasterized cell with 'X'. Use integer rasterization and include both endpoints. Inputs contain at least one row, and all coordinates are valid.

Constraints

1 <= len(board) <= 1000
1 <= len(board[0]) <= 1000
All rows have the same length
0 <= x0, x1 < len(board[0])
0 <= y0, y1 < len(board)
The board contains only 'O' before drawing

Function Signature

def draw_line(board, x0, y0, x1, y1):

Your question is Draw a Line on a Board. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Constraints

1 <= len(board) <= 1000
1 <= len(board[0]) <= 1000
All rows have the same length
0 <= x0, x1 < len(board[0])
0 <= y0, y1 < len(board)
The board contains only 'O' before drawing

Function Signature

def draw_line(board, x0, y0, x1, y1):

Your question is Draw a Line on a Board. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.