# 05/15
https://hackmd.io/@-JG915ddTbSXM0tfs4kLTw/HkBKgO8r3
## hw1

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

int a(const void *a, const void *b) {
    int numA = *(int*)a;
    int numB = *(int*)b;

    if (numA < numB) {
        return -1;
    } else if (numA > numB) {
        return 1;
    } else {
        return 0;
    }
}
int b(const void *a, const void *b) {
    int numA = *(int*)a;
    int numB = *(int*)b;

    if (numA > numB) {
        return -1;
    } else if (numA < numB) {
        return 1;
    } else {
        return 0;
    }
}

int c(const void *a, const void *b) {
    int numA = *(int*)a;
    int numB = *(int*)b;

    int isOddA = numA % 2;
    int isOddB = numB % 2;

    if (isOddA && !isOddB) {
        return -1;
    } else if (!isOddA && isOddB) {
        return 1;
    } else if (isOddA && isOddB) {
        if (numA < numB) {
            return -1;
        } else if (numA > numB) {
            return 1;
        } else {
            return 0;
        }
    } else {
        return 0;
    }
}

int main() {
    int arr[] = {9, 5, 2, 7, 1, 3, 6, 4, 8};
    int size = sizeof(arr) / sizeof(arr[0]);
    qsort(arr, size, sizeof(int), a);
    printf("small to large:\n");
    for (int i = 0; i < size; i++) 
    {
        printf("%d ", arr[i]);
    }
    printf("\n");
    qsort(arr, size, sizeof(int), b);
    printf("large to small:\n");
    for (int i = 0; i < size; i++) 
    {
        printf("%d ", arr[i]);
    }
    printf("\n");
    qsort(arr, size, sizeof(int), c);
    printf(" (odd numbers first, then even numbers, small to large):\n");
    for (int i = 0; i < size; i++)
    {
        printf("%d ", arr[i]);
    }
    printf("\n");
    return 0;
}