Easy - Sequence Equation.c

#include <assert.h>
#include <ctype.h>
#include <limits.h>
#include <math.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* readline();
char* ltrim(char*);
char* rtrim(char*);
char** split_string(char*);

int parse_int(char*);

/*
 * Complete the 'permutationEquation' function below.
 *
 * The function is expected to return an INTEGER_ARRAY.
 * The function accepts INTEGER_ARRAY p as parameter.
 */

/*
 * To return the integer array from the function, you should:
 *     - Store the size of the array to be returned in the result_count variable
 *     - Allocate the array statically or dynamically
 *
 * For example,
 * int* return_integer_array_using_static_allocation(int* result_count) {
 *     *result_count = 5;
 *
 *     static int a[5] = {1, 2, 3, 4, 5};
 *
 *     return a;
 * }
 *
 * int* return_integer_array_using_dynamic_allocation(int* result_count) {
 *     *result_count = 5;
 *
 *     int *a = malloc(5 * sizeof(int));
 *
 *     for (int i = 0; i < 5; i++) {
 *         *(a + i) = i + 1;
 *     }
 *
 *     return a;
 * }
 *
 */
int* permutationEquation(int p_count, int* p, int* result_count)
{
    int* result = malloc(p_count * sizeof(int));
    for(int i=1; i<=p_count; i++)
    {
        int search = 0;
        for(int k=0; k<2; k++)
        {
            if(search==0)
            {
                search = i;
            }
            for(int j=0; j<p_count; j++)
            {
                if(search==p[j])
                {
                    search = j+1;
                    break;
                }
            }
        }
        result[i-1] = search;
    }
    *result_count = p_count;
    return result;
}

int main()
{
    FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w");

    int n = parse_int(ltrim(rtrim(readline())));

    char** p_temp = split_string(rtrim(readline()));

    int* p = malloc(n * sizeof(int));

    for (int i = 0; i < n; i++)
    {
        int p_item = parse_int(*(p_temp + i));

        *(p + i) = p_item;
    }

    int result_count;
    int* result = permutationEquation(n, p, &result_count);

    for (int i = 0; i < result_count; i++)
    {
        fprintf(fptr, "%d", *(result + i));

        if (i != result_count - 1)
        {
            fprintf(fptr, "\n");
        }
    }

    fprintf(fptr, "\n");

    fclose(fptr);

    return 0;
}

char* readline()
{
    size_t alloc_length = 1024;
    size_t data_length = 0;

    char* data = malloc(alloc_length);

    while (true)
    {
        char* cursor = data + data_length;
        char* line = fgets(cursor, alloc_length - data_length, stdin);

        if (!line)
        {
            break;
        }

        data_length += strlen(cursor);

        if (data_length < alloc_length - 1 || data[data_length - 1] == '\n')
        {
            break;
        }

        alloc_length <<= 1;

        data = realloc(data, alloc_length);

        if (!data)
        {
            data = '\0';

            break;
        }
    }

    if (data[data_length - 1] == '\n')
    {
        data[data_length - 1] = '\0';

        data = realloc(data, data_length);

        if (!data)
        {
            data = '\0';
        }
    }
    else
    {
        data = realloc(data, data_length + 1);

        if (!data)
        {
            data = '\0';
        }
        else
        {
            data[data_length] = '\0';
        }
    }

    return data;
}

char* ltrim(char* str)
{
    if (!str)
    {
        return '\0';
    }

    if (!*str)
    {
        return str;
    }

    while (*str != '\0' && isspace(*str))
    {
        str++;
    }

    return str;
}

char* rtrim(char* str)
{
    if (!str)
    {
        return '\0';
    }

    if (!*str)
    {
        return str;
    }

    char* end = str + strlen(str) - 1;

    while (end >= str && isspace(*end))
    {
        end--;
    }

    *(end + 1) = '\0';

    return str;
}

char** split_string(char* str)
{
    char** splits = NULL;
    char* token = strtok(str, " ");

    int spaces = 0;

    while (token)
    {
        splits = realloc(splits, sizeof(char*) * ++spaces);

        if (!splits)
        {
            return splits;
        }

        splits[spaces - 1] = token;

        token = strtok(NULL, " ");
    }

    return splits;
}

int parse_int(char* str)
{
    char* endptr;
    int value = strtol(str, &endptr, 10);

    if (endptr == str || *endptr != '\0')
    {
        exit(EXIT_FAILURE);
    }

    return value;
}