日志16

二分查找

#include<iostream>

#include<cstdio>

#include<algorithm>

using namespace std;

const int N = 1e3 + 5;

int n, m;

int a[N];

void binarySearch(int m)

{

//left:序列的左端位置，right:序列的右端位置

int left = 0, right = n - 1;

int mid; //序列的中间位置

/****** 请补充以下的while循环******/

while(left < right)

{

int mid= (left+right)/2;

if(m<a[mid]){

right=mid;}

else

left=mid+1;}

if(m==a[left-1])

cout<<"YES"<<endl;

else cout<<"NO"<<endl;

}

int main()

{

cin >> n;

for(int i = 0 ; i < n ; i++)

{

cin >> a[i];

}

sort(a, a+n); //从小大进行排序

cin >> m;

binarySearch(m);

return 0;

}#include<iostream>

#include<cstdio>

#include<algorithm>

using namespace std;

const int N = 1e3 + 5;

int n, m;

int a[N];

void binarySearch(int m)

{

//left:序列的左端位置，right:序列的右端位置

int left = 0, right = n - 1;

int mid; //序列的中间位置

/****** 请补充以下的while循环******/

while(left < right)

{

int mid= (left+right)/2;

if(m<a[mid]){

right=mid;}

else

left=mid+1;}

if(m==a[left-1])

cout<<"YES"<<endl;

else cout<<"NO"<<endl;

}

int main()

{

cin >> n;

for(int i = 0 ; i < n ; i++)

{

cin >> a[i];

}

sort(a, a+n); //从小大进行排序

cin >> m;

binarySearch(m);

return 0;

}v