Sorts an array and removes any duplicate elements.

quicksort.c

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

void swap(int* a, int i, int j) {
    int temp = a[i];
    a[i] = a[j];
    a[j] = temp;
    return;
}

int partition(int* a, int left, int right) {
    int pivot = left;
    ++left;
    while (left <= right) {
        if (a[left] <= a[pivot]) {
            swap(a, left, pivot);
            ++left;
            ++pivot;
        } else {
            swap(a, left, right);
            --right;
        }
    }
    return pivot;
}

void quicksort(int* a, int start, int end) {
    if (start < end) {
        int pivot = partition(a, start, end);
        quicksort(a, start, pivot - 1);
        quicksort(a, pivot + 1, end);
    }
}

void compress(int* a, int* size) {
    int i, j;
    for (i = 1; i < *size; ++i) {
        int item = a[i - 1];
        for (j = i; j < *size; ++j) {
            if (item == a[j]) {
                --*size;
                swap(a, j, *size);
            }
        }
    }
}

int main() {
    int size;
    printf("Enter the number of elements: ");
    scanf("%d", &size);
    int* items = (int*) malloc(size);
    printf("Enter the elements:\n");
    int i;
    for (i = 0; i < size; ++i) {
        printf("  [%d]: ", i);
        scanf("%d", items + i);
    }
    quicksort(items, 0, size - 1);
    compress(items, &size);
    printf("Sorted:\n");
    for (i = 0; i < size; ++i) {
        printf("  [%d]: %d\n", i, items[i]);
    }
    free(items);
    return 0;
}