Implement a flood-fill algorithm that propagates through a 2D character grid from a given starting cell, marking every reachable connected cell with the character F.

• The function receives char **tab (the grid), Point size (its width and height), and Point begin (the starting column and row).
• Read the character at begin before modifying anything, only cells that share that exact character and are connected to the origin are filled.
• Connectivity is strictly horizontal and vertical: up, down, left, right. Diagonal neighbours are ignored.
• Stop propagation at the grid boundaries and whenever a neighbour holds a different character.
• Declare Point inside flood_fill.c as shown in the prototype: void flood_fill(char **tab, Point size, Point begin);.

Implement a flood-fill algorithm that propagates through a 2D character grid from a given starting cell, marking every reachable connected cell with the character F.

• The function receives char **tab (the grid), Point size (its width and height), and Point begin (the starting column and row).
• Read the character at begin before modifying anything, only cells that share that exact character and are connected to the origin are filled.
• Connectivity is strictly horizontal and vertical: up, down, left, right. Diagonal neighbours are ignored.
• Stop propagation at the grid boundaries and whenever a neighbour holds a different character.
• Declare Point inside flood_fill.c as shown in the prototype: void flood_fill(char **tab, Point size, Point begin);.