CodeForces 732D Exams

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<ctime>
#include<iostream>
using namespace std;
typedef long long LL;
const double pi=acos(-1.0),eps=1e-10;
void File()
{
    freopen("D:\\in.txt","r",stdin);
    freopen("D:\\out.txt","w",stdout);
}
template <class T>
inline void read(T &x)
{
    char c = getchar();
    x = 0;
    while(!isdigit(c)) c = getchar();
    while(isdigit(c))
    {
        x = x * 10 + c - ‘0‘;
        c = getchar();
    }
}

int n,m;
int a[200010],b[200010];
long long t[200010];
bool flag[200010];

bool check(int x)
{
    memset(flag,0,sizeof flag);
    for(int i=1;i<=x;i++) a[i]=b[i];
    for(int i=x;i>=1;i--)
    {
        if(a[i]==0) continue;

        if(flag[a[i]]) a[i]=0;
        else flag[a[i]]=1;
    }

    long long sum=0; int cnt=0;
    for(int i=1;i<=x;i++)
    {
        if(a[i]==0) sum=sum+1;
        else
        {
            sum=sum-t[a[i]];
            cnt++;
        }
        if(sum<0) return 0;
    }
    if(cnt<m) return 0;
    return 1;
}

int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++) cin>>b[i];
    for(int i=1;i<=m;i++) cin>>t[i];
    int L=1,R=n,ans=-1;
    while(L<=R)
    {
        int mid=(L+R)/2;
        if(check(mid)) R=mid-1,ans=mid;
        else L=mid+1;
    }
    cout<<ans<<endl;
    return 0;
}