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:

1. Using BFS .
2. Using recursive DFS .
3. 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]]