FloodFill.cpp

#include<vector>
#include<iostream>
using namespace std;
void floodFill(vector<vector<int>>&grid, int x, int y, int oldColor, int newcolor)
{
    //check boundary conditions
    if (x < 0 || y < 0 || x >= grid.size() || y >= grid.size())
        return;
    //check if current point is previouscolor
    if (grid[x][y] != oldColor)
        return;
    if (grid[x][y] == newcolor)
        return;

    grid[x][y] = newcolor;
    //left
    floodFill(grid,x-1,y,oldColor, newcolor);
    //right
    floodFill(grid, x +1, y, oldColor, newcolor);
    //top
    floodFill(grid, x, y -1, oldColor, newcolor);
    //bottom
    floodFill(grid, x, y + 1, oldColor, newcolor);

}
void printgrid(vector<vector<int>>&grid)
{
    for (int x = 0; x < grid.size(); x++)
    {
        for (int y = 0; y < grid.size(); y++)
        {
            cout << grid[x][y];
        }
        cout << endl;
    }
}
int main()
{
    vector<vector<int>>grid =
    { 
    { 1, 1, 1, 1, 1, 1, 1, 1 },
    { 1, 1, 1, 1, 1, 1, 0, 0 },
    { 1, 0, 0, 1, 1, 0, 1, 1 },
    { 1, 2, 2, 2, 2, 0, 1, 0 },
    { 1, 1, 1, 2, 2, 0, 1, 0 },
    { 1, 1, 1, 2, 2, 2, 2, 0 },
    { 1, 1, 1, 1, 1, 2, 1, 1 },
    { 1, 1, 1, 1, 1, 2, 2, 1 },
    };
    int x = 4;
    int y = 4;
    printgrid(grid);
    //convert all 2s to 9
    floodFill(grid,x,y,grid[x][y],9);
    printgrid(grid);

    return 0;
}