Flood Fill

Author: anantkaushik

733-flood-fill.py

@@ -0,0 +1,52 @@
+"""
+Problem Link: https://leetcode.com/problems/flood-fill/
+
+An image is represented by a 2-D array of integers, each integer representing the pixel 
+value of the image (from 0 to 65535).
+Given a coordinate (sr, sc) representing the starting pixel (row and column) of the flood fill, 
+and a pixel value newColor, "flood fill" the image.
+To perform a "flood fill", consider the starting pixel, plus any pixels connected 4-directionally 
+to the starting pixel of the same color as the starting pixel, plus any pixels connected 
+4-directionally to those pixels (also with the same color as the starting pixel), and so on. 
+Replace the color of all of the aforementioned pixels with the newColor.
+
+At the end, return the modified image.
+
+Example 1:
+Input: 
+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]]
+Explanation: 
+From the center of the image (with position (sr, sc) = (1, 1)), all pixels connected 
+by a path of the same color as the starting pixel are colored with the new color.
+Note the bottom corner is not colored 2, because it is not 4-directionally connected
+to the starting pixel.
+Note:
+
+The length of image and image[0] will be in the range [1, 50].
+The given starting pixel will satisfy 0 <= sr < image.length and 0 <= sc < image[0].length.
+The value of each color in image[i][j] and newColor will be an integer in [0, 65535].
+"""
+class Solution:
+    def floodFill(self, image: List[List[int]], sr: int, sc: int, newColor: int) -> List[List[int]]:
+        m, n = len(image), len(image[0])
+        color = image[sr][sc]
+        
+        if color == newColor:
+          return image
+        
+        def dfs(i, j):
+          if image[i][j] == color:
+            image[i][j] = newColor
+            if i >= 1:
+              dfs(i-1, j)
+            if j >= 1:
+              dfs(i, j-1)
+            if i < m-1:
+              dfs(i+1, j)
+            if j < n-1:
+              dfs(i, j+1)
+              
+        dfs(sr, sc)
+        return image