Itsnp_challenge.c

/*This gist consists of the solution of ITSNP posted on April 28 
Link of the post " https://www.facebook.com/101470728764629/posts/336507348594298/ " 
Here's the solution in c ! */

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

int
main(int argc, char **argv)
{

        char *input, *unique_chars_list;

        int input_len, list_c;

        /* = PREREQUISITES = */

        /* argument checking */

        if (argc < 2) {

                fprintf(stderr, "usage: %s string\n", argv[0]);

                exit(EXIT_FAILURE);

        }

        input = argv[1];

        input_len = strlen(input);

        /* allocate memory for the list */

        unique_chars_list = malloc(sizeof(char) * input_len);

        list_c = 0;

        /* = ACTUAL WORK = */

        unique_chars_list[list_c++] = tolower(input[0]);

        for (int i = 1; i < input_len; i++) {

                if (tolower(input[i-1]) != tolower(input[i]))

                        unique_chars_list[list_c++] = tolower(input[i]);

        }

        unique_chars_list[++list_c] = '\0';

        /* Print output */

        printf("Input: '%s', Output: '%s'\n", input, unique_chars_list);

        /* cleanup */

        free(unique_chars_list);

        return EXIT_SUCCESS;

}