二分查找

//2022.12.2二分查找
#include<stdio.h>
#include<stdlib.h>

#define N 20
typedef struct sqlist
{
	int *elem;         
	int length;        
	int listsize;      
}sql;



sql L;

void InitList()
{
	L.elem=(int *)malloc(N*sizeof(int));  
	if(!L.elem)
		exit(0);						 
	L.listsize=N;                         
	L.length=0;							 
}

void input(int n)
{
	int i;
	printf("请输入值:");
	for(i=1;i<=n;i++)
		scanf("%d",&L.elem[i]);
	L.length=n;
}

void output()
{
	int i;
	for(i=1;i<=L.length;i++)
		printf("%d ",L.elem[i]);
	printf("\n");
}
int x=0;			

int binsearch(int key)
{
	int low,high,mid;
	low=1;
	high=L.length;
	

	while (low<=high)
	{
		x++;
		mid=(low+high)/2;
		if (key<L.elem[mid])
			high=mid-1;
		else if (key==L.elem[mid])
			return mid;
		else 
			low=mid+1;
		
	}
	return 0;

}
int main()
{
	int n,key;
	InitList();
	printf("请输入个数:");
	scanf("%d",&n);
	input(n);
	output();
	printf("请输入要查找的值:\n");
	scanf("%d",&key);
	if (binsearch(key)!=0)
		printf("查找成功,在:%d的位置",binsearch(key));
	else
		printf("查找失败!");
	printf("%d",x);
	return 0;
}