Implement flood fill using BFS and DFS

Q: Implement flood fill using BFS and DFS

This is a Coding & Algorithms interview question from Apple for Software Engineer roles. View the full question and solution on PracHub.

Q: How do I approach Coding & Algorithms interview questions?

Coding & Algorithms questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master coding & algorithms interviews.

Question

Loading...

Problem

You are given a 2D grid image of size m × n, where each cell contains an integer color value. You are also given a starting cell (sr, sc) and an integer newColor.

Perform a flood fill starting from (sr, sc):

Let oldColor = image[sr][sc] .
Recolor (sr, sc) and every cell 4-directionally connected (up, down, left, right) to (sr, sc) that has color oldColor to newColor .
Return the modified image .

If oldColor == newColor, the grid should remain unchanged.

Requirements

Write the solution in three ways:

Using BFS .
Using recursive DFS .
Using iterative DFS (explicit stack; no recursion).

Inputs / Outputs

Input: image: int[m][n] , sr: int , sc: int , newColor: int
Output: Modified image after flood fill.

Constraints (typical)

1 ≤ m, n ≤ 50
0 ≤ sr < m , 0 ≤ sc < n
Color values are non-negative integers.

Example

Given:

image = [[1,1,1],[1,1,0],[1,0,1]] , sr = 1 , sc = 1 , newColor = 2

Output:

[[2,2,2],[2,2,0],[2,0,1]]