C language classic exercises (2) - "bubble sort"“

C Interesting language exercises —— Bubble sort

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One 、 Introduction to bubble sort

Bubble sort （Bubble Sort）, Also known as settlement sequencing , The reason why it is called bubble sorting is that the algorithm will put relatively small （ Big ） Data like bubbles in the water gradually rise to the top of the array . meanwhile , more （ Small ） The data of will also sink to the bottom of the array step by step , This process needs to be repeated many times in the whole array range . Every time you execute , Compare two adjacent elements , And determine whether to exchange positions .

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Two 、 Principle of graphic interpretation

Pure manual drawing ！

3、 ... and 、 Code implementation

1. Code example

//  Bubble sort bubble sort
void Bubble_sort(int a[], int sz)
{
    
	int i = 0, j = 0;
	for ( i = 0; i < sz - 1; i++)//  The outer loop  sz-1  Time 
	{
    
		for (j = 0; j < sz - 1- i; j++)  //  Inner circulation 
		{
    
			if (a[j] > a[j + 1])
			{
    
					int temp = a[j];
					a[j] = a[j + 1];
					a[j + 1] = temp;
			}
		}
	}
}

//  Print array functions 
void print(int arr[],int sz)
{
    
	int i = 0;
	for ( i = 0; i < sz; i++)
	{
    
		printf("%d ", arr[i]);
	}
	printf("\n");
}

int main()
{
    
	int i = 0;
	int arr[10] = {
     2,1,8,6,9,7,3,5,4,0 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	printf(" Please input data :\n");
	for ( i = 0; i < sz; i++)
	{
    
		scanf("%d", arr + i);
	}
	//print(arr, sz); //  Print the array data before sorting 
	Bubble_sort(arr, sz);
	print(arr, sz);
	return 0;
}

2. Code parsing

Code parsing ： For the in the array sz（sz Is the number of array elements ） Number of execution sz -1 Operate in sequence , In the outer loop of each , Perform the following operations on the unsorted elements in the array ： Compare two adjacent elements , If the subscript is j The element of is greater than the subscript j + 1 The element is , Then exchange its position , Each judgment and exchange is counted as a bubble sorting completion , So after sz - 1 After several operations, you can arrange all the numbers from small to large .

explain ： Inner circulation j < sz - i - 1： Because there are sz Elements j It's from 0 Start , For the first time 9 Only after several comparisons can the largest number be exchanged to the last , Then the array subscript is 0~ 8 Then with Subscript to be 0(+1)~8(+1) Than the size , So when arr[j] by sz - 1 - 1 == 8 When It's over , And so on, the second round sz - 2 - 1…

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summary

Bubble sort in general , Easy to understand , The code implementation is simple and not complicated , But the only disadvantage is the low efficiency , Because in every exchange , An element can only be judged one by one and then exchanged , If in an array with large array elements , It is undoubtedly a shortcoming ！ So can the partners come up with a better solution ？ I hope to make progress with you ！
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