жадные алгоритмы 27

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

int readarr(FILE* fin, int* data, int cnt); //считываем данные из файла в массив
int readarr(FILE* fin, int* data, int cnt)
{
    for (int k = 0; k < cnt; k++)
    {
        if (fscanf(fin, "%d", data + k) != 1){
            return -1;
        }
    }
    return 0;
}

int sol(int* arr, int n);
int sol(int* arr, int n)
{
    int prev = 0;
    int c = 1;
    int f = 0;
    prev = arr[0];
    for (int i = 1; i < n; i++)
    {
        if (arr[i] - prev == 1)
        {
            c++;
        }
        else if (c > 2)
        {
            c = 1;
        }
        else
        {
            f = 1;
            break;
        }
        prev = arr[i];
        if ( i == (n - 1) & c != 0 & c < 3)
        {
            f = 1;
        }
    }
    return f;
}


int main(void)
{
    FILE* file;
    int* arr;
    int N;
    int ans = 0;

    if ((file = fopen("in.txt", "rt")) == NULL) {
        printf("Can't open input file!\n");
        return -1;
    }

    if (fscanf(file, "%d", &N) != 1) {
        printf("Can't read N!\n");
        fclose(file);
        return -1;
    }

    if (N < 1) {
        printf("Invalid N!\n");
        fclose(file);
        return -1;
    }

    if ((arr = (int*) malloc(N * sizeof(int))) == NULL)
    {
        printf("Can't allocate memory!\n");
        fclose(file);
        return -1;
    }


    if (readarr(file, arr, N) < 0) {
        printf("Can't read array 1!\n");
        fclose(file);
        free(arr);
    }

    if (sol(arr, N) == 0)
    {
        printf("can be divided\n");
    }
    else
    {
        printf("can NOT be divided\n");
    }
    free(arr);
    fclose(file);

    return 0;
}