Very stupid sort (trolling homework)

trollsort.c

/* http://codegolf.stackexchange.com/questions/16226/trolling-homework-questions-sorting */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>

void read_some_doubles(double **data, size_t *size)
{
    char buf[512], *endptr;
    double d;
    size_t capacity = 16;

    *size = 0;
    *data = malloc(sizeof(double) * capacity);
    while(fgets(buf, sizeof(buf), stdin)) {
        d = strtod(buf, &endptr);
        if(endptr == buf)
            continue;
        if(*size == capacity) {
            capacity = capacity * 3 / 2;
            *data = realloc(*data, sizeof(double) * capacity);
        }
        (*data)[(*size)++] = d;
    }
}

void worker(double *data, size_t size, size_t myid, int (*pipes)[2])
{
    char buf[256];
    size_t i;

    for(i = 0; i < size; i++)
        if(data[i] <= data[myid])
            close(pipes[i][1]);

    while(read(pipes[myid][0], &buf, 1) != 0)
        ;
    snprintf(buf, sizeof(buf), "%g\n", data[myid]);
    write(1, buf, strlen(buf));
    exit(0);
}

int main(void)
{
    double *data;
    size_t num, i;
    int (*pipes)[2];

    read_some_doubles(&data, &num);
    pipes = malloc(sizeof(int) * 2 * num);
    for(i = 0; i < num; i++)
        if(pipe(pipes[i]) < 0)
            perror("input too large"), exit(1);

    for(i = 0; i < num; i++)
        if(fork() == 0)
            worker(data, num, i, pipes);

    for(i = 0; i < num; i++)
        close(pipes[i][1]);

    for(i = 0; i < num; i++)
        wait(NULL);

    return 0;
}

trollsort_output.txt

$ gcc -Wall -O2 trollsort.c

$ echo 0 1 4.332 1e100 1 -12 99 | tr ' ' '\n' | ./a.out
-12
0
1
1
4.332
99
1e+100