# 程設實習課 week 11
## Q1 : use pointer to implement swap

#include <stdio.h>

void swap(, ) {
    ///to-do///
}

int main() {
    int a,b;
    
    scanf("%d %d", &a, &b);
    
    printf("before:\n");
    printf("%d %d\n", a, b);
    
    ///to-do///
    
    printf("after:\n");
    printf("%d %d\n", a, b);
}

input:
1 2 
    
output:
before:
1 2
after:
2 1

## Q2 : qsort

#include <stdio.h>

void swap(, ){
    ///to-do///
}

void QSORT(int *nums, int left, int right){  
    
    if(left>=right) return;
    
    int l=left+1;
    int r=right;
    int key=nums[left];
    
    ///to-do///
    
    QSORT();
    QSORT();
}

int main(void){
    
    int array[10];
    int len = sizeof(array) / sizeof(int);
    
    for(int i = 0; i < len; i++){
        scanf("%d",&array[i]);
    }
    
    QSORT(array,0,9);

    for(int i=0; i<10; i++){
        printf("%d ",array[i]);
    }
}

intput:
9 1 3 7 8 2 6 4 5 0
output:
0 1 2 3 4 5 6 7 8 9