flood-fill.rb

# @param {Integer[][]} image
# @param {Integer} sr
# @param {Integer} sc
# @param {Integer} new_color
# @return {Integer[][]}
def flood_fill(image, sr, sc, new_color)
  x_max = image.length - 1
  y_max = image[0].length - 1
  
  stack = [[sr, sc]]
  visited = {}
  flood_value = image[sr][sc]
  
  until stack.empty?
    x, y = stack.pop
    
    # Bail if we've visited this node
    next if visited[[x,y]]
    visited[[x,y]] = true
    
    # Bail if this node isn't the right value
    next unless image[x][y] == flood_value
    
    # Set color
    image[x][y] = new_color
    
    # Add neighbors to the stack
    stack << [x, y + 1] if y < y_max
    stack << [x, y - 1] if y > 0
    stack << [x + 1, y] if x < x_max
    stack << [x - 1, y] if x > 0
  end
  
  image
end