样例过，求解！

Diary_Of_Young @ 2024-07-20 16:59:17

#include<bits/stdc++.h>

using namespace std;

const int N=1e6+10;
int a[N],b[N];

int bsearch1(int a[],int l,int r,int p)
{
    while(l<r)
    {
        int mid=(l+r)>>1;
        if(a[mid]>=p)
        {
            r=mid;
        }
        else{
            l=mid+1;
        }
    }   
    return l;
}
int bsearch2(int a[],int l,int r,int p)
{
    while(l<r)
    {
        int mid=(l+r+1)>>1;
        if(a[mid]<=p)
        {
            l=mid;
        }
        else{
            r=mid-1;
        }
    }   
    return l;
}

int main()
{
    int n;
    int x;
    std::ios::sync_with_stdio(false);
    cin>>n>>x;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
        for(int i=1;i<=x;i++)
    {
        cin>>b[i];
    }
    for(int o=1;o<=x;o++)
    {
    int z=bsearch1(a,1,n,b[o]);
    int g=bsearch2(a,1,n,b[o]);
    if(a[z]!=a[g])
    {
        cout<<"-1 "<<endl;
        continue;
    }
    cout<<z<<" ";
    }
    return 0;
}

by haimingbei @ 2024-07-20 17:02:06

@Diary_Of_Young

#include<bits/stdc++.h>
using namespace std;
int n,m,a[1000005],b[100005],t;
int two(int x){
    int lt=1,rt=n;
    while (lt<rt){
        int mid=lt+(rt-lt)/2;
        if (a[mid]>=x) rt=mid;
        else lt=mid+1;
    }
    if (a[lt]==x) return lt; 
    else return -1;
}
int main(){
    cin>>n>>m;  
    for (int i=1;i<=n;i++)cin>>a[i];
    for (int i=1;i<=m;i++)cin>>b[i];
    for(int i=1;i<=m;i++){
        cout<<two(b[i])<<" ";
    }
    return 0;
}

我写的就那样，但是AC，你可以参考一下

by wuzhitong @ 2024-07-20 19:22:25

@Diary_Of_Young 我的代码：

#include<bits/stdc++.h>
using namespace std;
int a[1000001],k;
bool cheak(int i)
{
    if(k<=a[i])return 0;
    return 1;
}
int main()
{
    int n,m;
    cin>>n>>m;
    //快读
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0); 
    for(int i=1;i<=n;i++)cin>>a[i];
    while(m--)
    {
       cin>>k;
       int l=1,r=n,ans;
       while(l<=r)
       {
            int mid=(l+r)/2;
            if(cheak(mid)==1)l=mid+1;
            else r=mid-1,ans=mid; 
       }
       if(a[ans]==k)cout<<ans<<" ";
       else cout<<-1<<" ";
    }
}

(求关 QWQ