BillDivision.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 'bonAppetit' function below.
 *
 * The function accepts following parameters:
 *  1. INTEGER_ARRAY bill
 *  2. INTEGER k
 *  3. INTEGER b
 */

void bonAppetit(int bill_count, int* bill, int k, int b) {
    int billAmount = 0;
    for(int i = 0; i<bill_count; i++)
    {
        if (i == k)
        {
            continue;
        }
        billAmount +=bill[i];
    }
    if (b == billAmount/2)
    {
        printf("Bon Appetit");
    }
    else
    {
        printf("%d", (billAmount + bill[k])/2 - billAmount/2);
    }
}   

int main()
{
    char** first_multiple_input = split_string(rtrim(readline()));

    int n = parse_int(*(first_multiple_input + 0));

    int k = parse_int(*(first_multiple_input + 1));

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

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

    for (int i = 0; i < n; i++) {
        int bill_item = parse_int(*(bill_temp + i));

        *(bill + i) = bill_item;
    }

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

    bonAppetit(n, bill, k, b);

    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;
}