> ## Documentation Index
> Fetch the complete documentation index at: https://leetcode-py.wisl.dev/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> leetcode-py is a Python LeetCode practice environment generator with one CLI: lcpy. It is not a service or platform.
> Each problem is a directory under leetcode/ with README.md, solution.py, test_solution.py, helpers.py, and playground.ipynb. lcpy gen creates them from JSON templates bundled with the package.
> Examples are backed by tests; copy them verbatim.

# Flood Fill Python Solution with Tests

> Tested Python solution for LeetCode 733 with 12 pytest cases. Generate a practice environment with lcpy.

LeetCode 733, Easy. Topics: Array, Depth-First Search, Breadth-First Search, Matrix. [View on LeetCode](https://leetcode.com/problems/flood-fill/description/).

Generate this problem as a practice environment: tested reference solution, 12 [parametrized pytest cases](/practice/testing), and a playground notebook:

```bash theme={"theme":{"light":"github-light","dark":"github-dark"}}
lcpy gen -n 733   # by problem number
lcpy gen -s flood_fill   # by problem name
```

## Problem

You are given an image represented by an `m x n` grid of integers `image`, where `image[i][j]` represents the pixel value of the image. You are also given three integers `sr`, `sc`, and `color`. Your task is to perform a **flood fill** on the image starting from the pixel `image[sr][sc]`.

To perform a **flood fill**:

1. Begin with the starting pixel and change its color to `color`.
2. Perform the same process for each pixel that is **directly adjacent** (pixels that share a side with the original pixel, either horizontally or vertically) and shares the **same color** as the starting pixel.
3. Keep **repeating** this process by checking neighboring pixels of the *updated* pixels and modifying their color if it matches the original color of the starting pixel.
4. The process **stops** when there are **no more** adjacent pixels of the original color to update.

Return the **modified** image after performing the flood fill.

### Examples

![Example 1](https://assets.leetcode.com/uploads/2021/06/01/flood1-grid.jpg)

```
Input: image = [[1,1,1],[1,1,0],[1,0,1]], sr = 1, sc = 1, color = 2
Output: [[2,2,2],[2,2,0],[2,0,1]]
```

**Explanation:** From the center of the image with position `(sr, sc) = (1, 1)` (i.e., the red pixel), all pixels connected by a path of the same color as the starting pixel (i.e., the blue pixels) are colored with the new color. Note the bottom corner is not colored 2, because it is not horizontally or vertically connected to the starting pixel.

```
Input: image = [[0,0,0],[0,0,0]], sr = 0, sc = 0, color = 0
Output: [[0,0,0],[0,0,0]]
```

**Explanation:** The starting pixel is already colored with 0, which is the same as the target color. Therefore, no changes are made to the image.

### Constraints

* `m == image.length`
* `n == image[i].length`
* `1 <= m, n <= 50`
* `0 <= image[i][j], color < 2^16`
* `0 <= sr < m`
* `0 <= sc < n`

## Solution

Reference implementation from [solution.py on GitHub](https://github.com/wislertt/leetcode-py/blob/main/leetcode/flood_fill/solution.py), full suite in [test\_solution.py](https://github.com/wislertt/leetcode-py/blob/main/leetcode/flood_fill/test_solution.py):

```python theme={"theme":{"light":"github-light","dark":"github-dark"}}
class Solution:
    # Time: O(m*n)
    # Space: O(m*n)
    def flood_fill(self, image: list[list[int]], sr: int, sc: int, color: int) -> list[list[int]]:
        original = image[sr][sc]
        if original == color:
            return image

        def dfs(r: int, c: int) -> None:
            if r < 0 or r >= len(image) or c < 0 or c >= len(image[0]) or image[r][c] != original:
                return
            image[r][c] = color
            for dr, dc in [(1, 0), (-1, 0), (0, 1), (0, -1)]:
                dfs(r + dr, c + dc)

        dfs(sr, sc)
        return image
```

## Complexity

| Time    | Space   |
| ------- | ------- |
| O(m\*n) | O(m\*n) |

## Tags

[Grind 75](/catalog/grind-75), [Grind](/catalog/grind), [NeetCode All](/catalog/neetcode).