#include <iostream>
using namespace std;
int SeqSearch(int r[],int n,int k)
{
 r[0]=k;//下標(biāo)0用作哨兵存放要查詢的數(shù)
 int i=n;
 while(r[i]!=k)//不用判斷下標(biāo)i是否越界
 {
 i--;
 }
 return i;
}
int main()
{
 int n;
 cout<<"請輸入數(shù)組元素個數(shù)："<<endl;
 cin>>n;
 int a[n+1];

 cout<<"請輸入數(shù)組元素："<<endl;
 for(int i=1;i<=n;i++)
 {
 cin>>a[i];
 }
 int k;
 cout<<"請輸入要查詢的數(shù)："<<endl;
 cin>>k;
 for(int i=1;i<=n;i++)
 {
 cout<<a[i]<<" ";
 }
 cout<<endl;
 cout<<"該數(shù)在數(shù)組中的位置為：";
 cout<<SeqSearch(a,n,k);
 return 0;
}

#include<iostream>
using namespace std;
int BinSearch1(int r[],int n,int k)//非遞歸
{
 int low=1,high=n;//設(shè)置查找區(qū)間
 while(low<=high)//如果區(qū)間存在
 {
 int mid=(low+high)/2;
 if(k<r[mid])high=mid-1;//查找在左半?yún)^(qū)進行，回到while那一步
 else if(k>r[mid])low=mid+1;
 else return mid;
 }
 return 0;//如果區(qū)間不存在，則返回0，查找失敗

}
int BinSearch2(int r[],int low,int high,int k)//遞歸
{
 int mid=(low+high)/2;
 if(low>high) return 0;
 else
 {
  if(k<r[mid])BinSearch2(r,low,mid-1,k);
  else if(k>r[mid])BinSearch2(r,mid+1,high,k);
  else return mid;
 }

}
int main()
{
 int n;
 cout<<"請輸入數(shù)組元素個數(shù)：";
 cout<<endl;
 cin>>n;
 int a[n+1];

 cout<<"請輸入數(shù)組元素：";
 cout<<endl;
 for(int i=1;i<=n;i++)
 {
 cin>>a[i];
 }
 cout<<"請輸入要查找的數(shù)：";
 cout<<endl;
 int k;
 cin>>k;
 cout<<"該數(shù)在數(shù)組中的位置是："<<endl;
 cout<<BinSearch1(a,n,k);cout<<endl;
 cout<<BinSearch2(a,1,n,k);
}