Flood fill algorithm in C (recursive)

flood.c

/*
Recursive flood algorithm in C (clean and fast approach)
No license, but post the project and tag me if you used it in anything, would love to see it :)
*/

// Libraries
#include <stdio.h>
#include <time.h>

// Screen
unsigned int screen[5][5] = {
    { 0, 5, 5, 5, 0 }, 
    { 5, 0, 5, 0, 5 }, 
    { 5, 0, 0, 0, 5 }, 
    { 5, 0, 0, 0, 5 }, 
    { 0, 5, 5, 5, 0 }, 
};

// Puts a character on the screen
void put(int x, int y, unsigned char c) {
    if (x >= 0 && x < 5 && y >= 0 && y < 5) {
        screen[y][x] = c;
    }
}

// Gets a character
int get(int x, int y) {
    if (x >= 0 && x < 5 && y >= 0 && y < 5) {
        return screen[y][x];
    }
    
    return -1;
}

// Flood fill
void flood(int x, int y, unsigned char c, unsigned char o) {
    if (get(x, y) != -1 && get(x, y) == o) {
        put(x, y, c);
        flood(x + 1, y,     c, o);
        flood(x - 1, y,     c, o);
        flood(x,     y + 1, c, o);
        flood(x,     y - 1, c, o);
    }
}

// Displays
void display() {
    for (unsigned int y = 0; y < 5; y++) {
        for (unsigned int x = 0; x < 5; x++) {
            putchar(screen[y][x] + '0');
            putchar(' ');
        }
        putchar('\n');
    }
}

// Main
int main(int argc, char *argv[]) {
    clock_t start = clock();
    flood(1, 1, 3, get(1, 1));
    printf("Finished in %d milliseconds! \n\n", clock() - start);
    display();
    
    return 0;
}