update flood fill.py

Author: kumailn

Python/Flood_Fill.py

@@ -1,16 +1,33 @@
-def floodFill(image, sr, sc, newColor):
+#Question: Given a image (2D list), a x and y coordinate of a pixel, and a new color, flood fill all neigbboring pixels with the same color to the new color
+#Solution: Run a DFS on the input pixel
+#Difficulty: Easy
+
+from typing import List
+def floodFill(image: List[List[int]], sr: int, sc: int, newColor: int) -> List[List[int]]:
+        
+        #If the pixel at the given coordinates is already the new color, return the image
         if image[sr][sc] == newColor: return image
+
+        #Define a recursive DFS to help us flood fill
         def dfs(i, j, newColor, oldColor, image):
-            if i >= 0 and j >= 0 and i < len(image) and j < len(image[0]) and image[i][j] == oldColor:
-                image[i][j] = newColor
-                dfs(i + 1, j, newColor, oldColor, image)
-                dfs(i - 1, j, newColor, oldColor, image)
-                dfs(i, j + 1, newColor, oldColor, image)
-                dfs(i, j - 1, newColor, oldColor, image)
+
+                #If the coordinates passed are not out of bounds and the color is the same as the previous one
+                if i >= 0 and j >= 0 and i < len(image) and j < len(image[0]) and image[i][j] == oldColor:
+
+                        #Set the pixel at the given coordinates to the new color
+                        image[i][j] = newColor
+
+                        #Recursively repeat on the pixel left, right, above and below
+                        dfs(i + 1, j, newColor, oldColor, image)
+                        dfs(i - 1, j, newColor, oldColor, image)
+                        dfs(i, j + 1, newColor, oldColor, image)
+                        dfs(i, j - 1, newColor, oldColor, image)
+
+        #Call our DFS function on the original inputs
         dfs(sr, sc, newColor, image[sr][sc], image)
         return image
 
 def main():
-    print(floodFill([[0,0,0],[0,1,1]], 1, 1, 1))
+    print(floodFill([[0,0,0],[0,1,1]], 0, 0, 6))
 
-main()hhh
+main()