@rf Настигло меня немного новогоднее настроение и я написал небольшую, но интересную програмку на Си. Она генерирует гирлянду из 4 цветов и ищет в ней последовательности из 4 разных цветов.

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <time.h>

#define RED "\033[1;31m#"
#define YELLOW "\033[1;33m#"
#define BLUE "\033[1;34m#"
#define GREEN "\033[1;32m#"
#define RESET "\033[0m"

#define RED_FLAG 8
#define YELLOW_FLAG 4
#define BLUE_FLAG 2
#define GREEN_FLAG 1

static char* lightbulbs[] = {RED, YELLOW, BLUE, GREEN};
static int flags[] = {RED_FLAG, YELLOW_FLAG, BLUE_FLAG, GREEN_FLAG};

typedef struct Garland {
    char* lightbulbs;
    unsigned int length;
} Garland;

Garland generate_garland(unsigned int length); 
void print_garland(Garland* g);
int* find_four_different_colors_sequences_in_garland(Garland* g);

int main () {
    srand(time(0));
    Garland g = generate_garland(100);
    print_garland(&g);
    find_four_different_colors_sequences_in_garland(&g);
}

Garland generate_garland(unsigned int length) {
    Garland g;
    g.lightbulbs = malloc(length * sizeof(char*));
    g.length = length;
    for (unsigned int i = 0; i < length; i ++) {
        g.lightbulbs[i] = rand() % 4;
    }
    return g;
}

void print_garland(Garland* g) {
    for (unsigned int i = 0; i < g->length; i ++) {
        printf("%s", lightbulbs[g->lightbulbs[i]]);
    }
    printf(RESET);
    printf("\n");
}

int* find_four_different_colors_sequences_in_garland(Garland* g) {
    // [0000rybg]
    int amount_of_answers = 0;
    int *answers = malloc(sizeof(int) * amount_of_answers);
    char flag = 0x0;
    
    for (unsigned int i = 0; i < g->length; i ++) {
        flag = flag ^ flags[g->lightbulbs[i]];
        if (!(flag & flags[g->lightbulbs[i]])) {
            flag = 0x0;
            i --;
            continue;
        }
        if ((flag ^ 0xf) == 0) {
            amount_of_answers += 1;
            answers = realloc(answers, amount_of_answers * sizeof(int));
            answers[amount_of_answers-1] = i - 3;
            flag = 0x0;
        }
    }

    printf("%i\n", amount_of_answers);

    for (int i = 0; i < amount_of_answers; i ++) {
        printf("place %i: %i (", i, answers[i]);
        for (int j = answers[i]; j < answers[i] + 4; j ++) {
            printf("%s", lightbulbs[g->lightbulbs[j]]);
        }
        printf(RESET);
        printf(")\n");
    }

    return answers;
}