题解

#include<bits/stdc++.h>
using namespace std;
int a[105];
int n,x;
int main(){
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i];
    }cin>>x;
    int l=1,r=n;
    int ans=-1;
    while(l<=r){
        int mid=(l+r)/2;
        if(a[mid]==x){
            ans=mid;
            break;
        }
        else if(a[mid]>x){
            r=mid-1;
        }
        else if(a[mid]<x){
            l=mid+1;
        }
    }
    cout<<ans;
    return 0;
}