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Grokking the Coding Interview Patterns in Go

Solution: Flood Fill

Explore how to solve the flood fill problem using a depth-first search approach combined with backtracking. This lesson guides you through updating connected pixels of the same color by recursively checking neighbors until the fill is complete. Understand how to implement the algorithm correctly, manage boundaries, and evaluate its time and space complexities in grid-based challenges.

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Statement

You are given a 2D grid of size m x n, where grid[i][j] represents the pixel value at position (i, j).

Additionally, you are given three integers:

  • sr: The row index of the starting pixel

  • sc: The column index of the starting pixel

  • target: The new color to apply

Your task is to perform a flood fill starting from the pixel at position (sr, sc). Below is the flood fill process:

  1. If the pixel at (sr, sc) already has the value target, return the original grid without any changes.

  2. Otherwise, start at the pixel grid[sr][sc] and change its color to the given color target. ...