dict-encode.c

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

typedef struct {
    char string[1024];
} String;

typedef struct {
    int size;
    String dict[1024];
} CharDict;

void print_dict(CharDict* dict) {
    int i;
    for(i=0; i<dict->size; ++i) {
        printf("%d %s\n", i, dict->dict[i].string);
    }
}

void add_element(CharDict* dict, String* string) {
    memcpy(dict->dict[dict->size].string, string, sizeof(String));
    dict->size += 1;
}

void clean_dict(CharDict* dict) {
    dict->size = 1;
    dict->dict[0].string[0] = '\0';
}

int is_in_dict(CharDict* dict, char* string) {
    int i;
    for(i=0; i<dict->size; ++i) {
        if (strcmp(dict->dict[i].string, string) == 0) {
            return 1;
        }
    }
    return 0;
}

void init_dict(CharDict* dict, String* string) {
    int i;
    char chr[2];
    i = 0;
    while((chr[0] = string->string[i]) != '\0') {
        i++;
        chr[1] = '\0';
        if (!is_in_dict(dict, chr)) {
            String string;
            strcpy(string.string, &chr);
            string.string[1] = '\0';
            add_element(dict, &string);
        }
    }
}

int index_of(CharDict* dict, String* string) {
    int i;
    for(i=0; i<dict->size; ++i) {
        if (strcmp(dict->dict[i].string, string->string) == 0) {
            return i;
        }
    }
    return -1;
}

void add_char_to_str(char* string, char chr) {
    int size = strlen(string);
    string[size] = chr;
    string[size + 1] = '\0';
}

char* encode(CharDict* dict, String* string) {
    clean_dict(dict);
    init_dict(dict, string);
    int i, idx;
    char chr;
    char output[1024] = "";
    char prefix[1024] = "";
    char temp[1024] = "";
    i = 0;
    while((chr = string->string[i]) != '\0') {
        i += 1;
        strcpy(temp, prefix);
        add_char_to_str(temp, chr);
        if (is_in_dict(dict, temp)) {
            add_char_to_str(prefix, chr);
        } else {
            idx = index_of(dict, prefix);
            if (idx == -1) {
                printf("Error\n");
                exit(EXIT_FAILURE);
            }
            add_char_to_str(output, (idx + 48));
            add_char_to_str(prefix, chr);
            add_element(dict, prefix);
            prefix[0] = chr;
            prefix[1] = '\0';
        }
    }
    return output;
}

int main(int argc, char* argv[]) {
    CharDict cdict;
    printf("%s\n", encode(&cdict, argv[1]));
    return 0;
}