Couting unique elements, with a peculiar definition of equality.

elements.c

#include "elements.h"

#include <stddef.h>
#include <stdbool.h>

static int compare(const element *a, const element *b)
{
    if (a->e2 == b->e2)
        return 0;
    else if (a->e1 != b->e1)
        return b->e1 - a->e1;
    return b->e2 - a->e2;
}

size_t count_unique(const element *s)
{
    size_t c = 0;
    bool found;
    for (size_t i = 0; s[i].s != NULL; ++i) {
        found = false;
        for (size_t j = 0; j < i; ++j) {
            if (compare(&s[i], &s[j]) == 0) {
                found = true;
                break;
            }
        }
        if (!found)
            c++;
    }
    return c;
}

elements.h

#ifndef ELEMENTS_H
#define ELEMENTS_H

#include <stddef.h>

typedef struct
{
    const char *s;
    int e1;
    int e2;
} element;

size_t count_unique(const element *s);



#endif