C語言筆試題（17）——三種常見的排序

1、直接插入排序

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

void insert_sort(int a[], int n)
{
    int i, j;

    for (i = 2; i < n; i++)    //第二個紀錄開始插入n - 1趟   
    {
        a[0] = a[i];   //設置監視哨
        j = i - 1;

        while(a[0] < a[j])   
        {
            a[j + 1] = a[j];   //後移一個位置
            j--;
        }

        a[j + 1] = a[0];
    }

    return ;
}

int main(int argc, const char *argv[])
{
    int i;
    int a[11] = {0, 2, 5, 1, 56, 34, 23, 67, 52, 68, 102};

    for (i = 1; i < 11; i++)
        printf("%d ", a[i]);
    printf("\n");
    
    insert_sort(a, 11);

    for (i = 1; i < 11; i++)
        printf("%d ", a[i]);
    printf("\n");

    return 0;
}

2、冒泡排序

#include <stdio.h>

void sort(int a[], int n)
{
    int i, j;
    int temp, flag;;

    for (i = 1; i < n; i++)    //n - 1趟
    {
        flag = 0;       //交換標誌

        for (j = n -1; j >= i; j--)
        {
            if (a[j] < a[j - 1])
            {
                temp = a[j];
                a[j] = a[j - 1];
                a[j - 1] = temp;
                flag = 1;
            }
        }

        if (flag == 0)
            break;
    }

    return ;
}

int main(int argc, const char *argv[])
{
    int i;
    int a[10] = {99, 4, 5, 23, 12, 56, 35, 57, 98, 45};

    sort(a, 10);

    for (i = 0; i < 10; i++)
        printf("%d ", a[i]);
    printf("\n");

    return 0;
}

3、直接選擇排序

#include <stdio.h>

void select_sort(int a[], int n)
{
    int i, j, m;
    int temp;

    for (i = 0; i < n - 1; i++)   //n - 1趟
    {
        m = i;

        //篩選出最小的數
        for (j = i + 1; j < n; j++)   
        {
            if (a[j] < a[m])
                m = j;
        }

        if (m != i)
        {
            temp = a[i];
            a[i] = a[m];
            a[m] = temp;
        }
    }

    return ;
}

int main(int argc, const char *argv[])
{
    int i;
    int a[] = {43, 23, 45, 56, 21, 67, 4, 2, 64, 25};

    select_sort(a, 10);

    for (i = 0; i < 10; i++)
        printf("%d ", a[i]);
    printf("\n");

    return 0;
}