冒泡排序法

#include<stdio.h>
#include<assert.h>

void display(int * a, int n) 
{
	for(int i = 0; i < n; i++)
	{
		printf("%d,",a[i]);
	}
	printf("\n");
}

void swap(int * a, int * b)
{
	int temp;
	temp = *a;
	*a = *b;
	*b = temp;
}

void bubble_sort(int * a, int n)
{  
  int i = 0;
  int j ;
  for(i = 0; i < n-1; i++ )
  {
	  for( j = i; j <= n-1; j++ )
	  {
		  if(a[j] >=  a[i])
		  {
			  swap(&(a[j]), &(a[i]));
		  }
	  }
  }

}

int main()
{   
	int a[8] ={2, 1, 3, 4, 5, 7, 6, 8};
	int num = sizeof(a)/sizeof(int);
	printf("before_sort:");
	display(a, num);
	bubble_sort(a,num);
	printf("after_sort:");
	display(a, num);
	return 0;
	
}

#include <stdio.h>
#include <time.h>

//交換兩個數據
void swap(int *a, int *b)
{
	int temp;
	temp = *a;
	*a = *b;
	*b = temp;
}

//顯示交換後的數組
void display_array( int a[], int n )
{
    int i;
    for( i = 0; i < n; i++ )
        printf( "%d ", a[i] );
}

//冒泡排序
void bubble_sort( int a[], int n )
{

	int i ,j;
	int flag = 1;  //判斷比較中是否發生了交換 1代表進行了交換
	for(i = 0; i<n-1 && flag; i++ )    //flag的作用：若上次排序沒有發生交換，就說明數組已經是有序
	{                                  //這樣做可以減少不必要的後續比較
		flag = 0;
		for(j = n -1; j >=i; j-- )  //第一次比較時 j是 0 ~ 7 第二次是  1 ~ 7
		{
			if(a[j] > a[j + 1])
			{	
				swap(&(a[j]), &(a[j+1]));
			    flag = 1;
			}
		}
	}

}

int main()
{
    clock_t start, finish;
    start = clock();
    int  n = 8;
    int a[] = { 2, 1, 3, 4, 5, 7, 6, 8 };
    printf( "Before sorting: " );
    display_array( a, n );
    bubble_sort( a, n );
    printf( "After sorting: " );
    display_array( a, n );
    finish = clock();
    printf("\n本次計算一共耗時: %f秒\n\n", (double)(finish-start)/CLOCKS_PER_SEC);
    return 0;
}