1366E - Two Arrays - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;
typedef long long  ll;
const ll mod=998244353;
const ll mx=3e5;
#define ff first
#define ss second
#define pi pair<ll,ll>
#define pii pair<pi,ll>
#define memo(a,b) memset(a,b,sizeof(a))
#define pb push_back
#define MAX3(a,b,c) max(a,max(b,c))
#define MIN3(a,b,c) min(a,min(b,c))
#define V vector<ll>
#define VP vector<pi>
#define all(a) a.begin(),a.end()
#define PI acos(-1)
#define all(a) a.begin(),a.end()
#define check(a,b) ((1ll<<a)&b)
ll bigmod(ll b,ll p)
{
    if(p==0)return 1;
    if(p%2==0)
    {
        ll h=bigmod(b,p/2);
        return (h*h)%mod;
    }
    else
    {
        return (b*(bigmod(b,p-1)))%mod;
    }
}
void solve()
{
 ll n,m;
 cin>>n>>m;
 map<ll,vector<ll>>xx;
 ll a[n+10];
 ll b[m+10];
 for(ll i=1;i<=n;i++)
 {
     cin>>a[i];

 }
 ll p[n+10];
 p[n+1]=1e18;
 for(ll i=n;i>=1;i--)p[i]=min(a[i],p[i+1]);
 for(ll i=1;i<=n;i++)
 {
     //if(p[i]==a[i])
     xx[p[i]].pb(i);
     //cout<<p[i]<<" ";
 }
 for(ll i=1;i<=m;i++)cin>>b[i];
 for(ll i=1;i<=m;i++)
 {
     if(!xx[b[i]].size()||p[1]!=b[1])
     {
         cout<<0<<"\n";return;
     }
 }
 ll ans=1;
 for(ll i=2;i<=m;i++)
 {
     //cout<<xx[b[i]].back()<<" "<<xx[b[i-1]][0]<<"\n";
     //if(xx[b[i]].size()==1)continue;
     ans=(ans*(xx[b[i]].back()-xx[b[i]][0]+1))%mod;
 }
 cout<<ans<<"\n";

}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);

//ll t;cin>>t;while(t--)
solve();
return 0;
}