Flood-Fill algoritms

#include<iostream>
using namespace std;

#define M 9
#define N 9

void color(int field[][N], int x, int y, int pc, int nc)
{
    if (x < 0 || x >= M || y < 0 || y >= N)
        return;
    if (field[x][y] != pc)
        return;

    field[x][y] = nc;

    color(field, x+1, y, pc, nc);
    color(field, x-1, y, pc, nc);
    color(field, x, y+1, pc, nc);
    color(field, x, y-1, pc, nc);
}

void ff(int field[][N], int x, int y, int nc)
{
    int pc = field[x][y];
    color(field, x, y, pc, nc);
}

int main()
{
    int field[M][N] = {
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 0, 0, 0},
    };

    int x = 5, y = 5, nc = 1;
    ff(field, x, y, nc);

    for (int i=0; i<M; i++){
        for (int j=0; j<N; j++){
            cout << field[i][j] << " ";
        }
        cout << endl;
    }
}