排序算法(重温基础排序算法，C语言)

最新推荐文章于 2024-06-22 20:16:46 发布

原创最新推荐文章于 2024-06-22 20:16:46 发布 · 156 阅读

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本文深入讲解了三种排序算法：冒泡排序、快速排序和归并排序。每种算法都通过C语言实现，详细展示了排序过程，包括算法的基本思想、代码实现及运行结果，帮助读者理解排序算法的工作原理。

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1.冒泡排序

#include<stdio.h>

void sort_bubble(int arr[],int length){

	for(int i=0;i<length;i++){
		printf("before times sort: %d\n",i);
		for(int k = 0 ;k<length;k++){
			printf("%d\n", arr[k]);
		}
		for(int j=0;j<length-i-1;j++){
			int tmp;
			if(arr[j] < arr[j+1]){
				tmp = arr[j+1];
				arr[j+1] = arr[j];
				arr[j] = tmp;
			}

		}
		
		printf("after times sort: %d\n",i);
		for(int k = 0 ;k<length;k++){
			printf("%d\n", arr[k]);
		}
	}
}
int main(){
	int arr[5] = {13,2,4,3,14};
	
	int length = sizeof(arr)/sizeof(arr[0]);
	printf("start: \n");
	for(int k = 0 ;k<length;k++){
		printf("%d\n", arr[k]);
	}
	sort_bubble(arr,length);
	printf("result:\n");
	for(int i = 0 ;i<length;i++){
		printf("%d\n", arr[i]);
	}
	return 0;
}

2.快速排序

#include<stdio.h>
#include<stdlib.h>
int* sort_fast(int arr[],int length){
	if(length <= 1){
		return arr;
	}
	int left_num = 0;
	int right_num = 0;
	for(int i=1;i<length;i++){
		//arr[0] 为基准数字
		if(arr[0] > arr[i]){
			left_num ++;
		}else{
			right_num ++;
		}
	}
	int *left_arr,*right_arr;
	left_arr = (int*)malloc(sizeof(int)*left_num);
	//left_arr = (int*)calloc(left_num,sizeof(int));
	right_arr = (int*)malloc(sizeof(int)*right_num);
	//right_arr = (int*)calloc(right_num,sizeof(int));
	int j=0,k=0;
	int base_num = arr[0];
	printf("sort start... length %d base_num %d\n",length,base_num);
	for(int i=1;i<length;i++){
		if(base_num > arr[i]){
			left_arr[j++] = arr[i];
			printf("left %d\n", arr[i]);
		}else{
			right_arr[k++] = arr[i];
			printf("right %d\n", arr[i]);
		}
	}
	left_arr = sort_fast(left_arr,left_num);
	right_arr = sort_fast(right_arr,right_num);

	int *total_arr;
	int total_num = left_num+right_num;
	total_arr = (int*)malloc(sizeof(int)*total_num);
	int index = 0;
	for(int i=0;i<left_num;i++){
		total_arr[index++] = left_arr[i];
	}
	printf("left_num %d\n", index);
	printf("base_num %d\n", base_num);
	total_arr[index++] = base_num;

	for(int i=0;i<right_num;i++){
		total_arr[index++] = right_arr[i];
	}
	free(left_arr);
	free(right_arr);
	printf("finnal...\n");
	for(int i=0;i<length;i++){
		printf("%d\n", total_arr[i]);
	}
	return total_arr;
}
int main(){
	int arr[5] = {13,2,4,3,14};
	
	int length = sizeof(arr)/sizeof(arr[0]);
	printf("start: \n");
	for(int k = 0 ;k<length;k++){
		printf("%d\n", arr[k]);
	}
	int *new_arr = (int*)malloc(sizeof(int)*length);
	new_arr = sort_fast(arr,length);
	printf("result:\n");
	for(int i = 0 ;i<length;i++){
		printf("%d\n", new_arr[i]);
	}
	return 0;
}

3.归并排序

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
void merge(int arr[],int left,int mid,int right){
	int *tmp_arr;
	int tmp_num = right - left + 1;
	tmp_arr = (int*)malloc(sizeof(int)*tmp_num);

	int i=left,j=mid+1,k=0;
	while(i<=mid && j<=right){
		if(arr[i] < arr[j]){
			tmp_arr[k++] = arr[i++];
		}else{
			tmp_arr[k++] = arr[j++];
		}
	}
	while(i<=mid){
		tmp_arr[k++] = arr[i++];
	}
	while(j<=right){
		tmp_arr[k++] = arr[j++];
	}
	printf("sort after... left %d mid %d right %d\n",left,mid,right);
	for(i=left,j=0;i<=right;i++,j++){
		arr[i] = tmp_arr[j];
		printf("%d\n", arr[i]);
	}
	free(tmp_arr);
}
void sort_merge(int arr[],int left,int right){
	if(left < right){
		int mid;
		mid = floor((left+right)/2);
		printf("sort start... left %d mid %d right %d\n",left,mid,right);
		for(int i=left;i<=right;i++){
			printf("%d\n", arr[i]);
		}
		sort_merge(arr,left,mid);
		sort_merge(arr,mid+1,right);
		merge(arr,left,mid,right);
	}
}
int main(){
	int arr[5] = {13,2,4,3,14};
	
	int length = sizeof(arr)/sizeof(arr[0]);
	printf("start: \n");
	for(int k = 0 ;k<length;k++){
		printf("%d\n", arr[k]);
	}
	sort_merge(arr,0,length - 1);
	printf("result:\n");
	for(int i = 0 ;i<length;i++){
		printf("%d\n", arr[i]);
	}
	return 0;
}