Untitled

#include <stdio.h>

enum Constants {
    SEQUENCE_SIZE = 10,
};

int checkRepeat(int *a, int size) {
    int repeat[SEQUENCE_SIZE] = {0};
    for (int i = 0; i < size; ++i) {
        if (a[i] >= 10 || a[i] < 0)
            return 1;

        repeat[a[i]]++;
        if (repeat[a[i]] > 1)
            return 1;
    }
    return 0;
}

void swap(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

unsigned nextPermutation(int *a, int size) {
    int i = size - 2;
    while (i >= 0 && a[i] > a[i + 1])
        i--;
    if (i == -1)
        return 0;

    for (int j = i + 1, k = size - 1; j < k; j++, k--)
        swap(&a[j], &a[k]);

    int j = i + 1;
    while (a[j] < a[i])
        j++;
    swap(&a[i], &a[j]);
    return 1;
}

int main() {
    int size = 0;
    int flagBadInput = 0;
    char currentChar;
    int a[SEQUENCE_SIZE];
    for (int i = 0; i < SEQUENCE_SIZE + 1; i++) {
        if (scanf("%c", &currentChar) < 1 || (currentChar != '\n' && i == SEQUENCE_SIZE)) {
            printf("%c", currentChar);
            flagBadInput = 1;
            break;
        }
        if (currentChar == '\n') {
            break;
        }
        size++;
        a[i] = currentChar - '0';
    }
    int count;
    int printable = 0;
    if (scanf("%d", &count) < 1 || flagBadInput || checkRepeat(a, size)) {
        printf("bad input");
        return 0;
    }
    while (nextPermutation(a, size) && printable < count) {
        printable++;
        for (int i = 0; i < size; i++)
            printf("%d", a[i]);
        printf("\n");
    }
    return 0;
}