Submission #412246

#	Time	Username	Problem	Language	Result	Execution time	Memory
412246		Theo830	Exam (eJOI20_exam)	C++17	100 / 100	201 ms	98676 KiB

exam

#include <bits/stdc++.h>
using namespace std;
typedef int ll;
ll INF = 1e9+7;
ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ii,ll>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
ll seg[400005]={0};
void update(ll s,ll e,ll qs,ll qe,ll idx,ll k){
    if(s == e && s == qs){
        seg[idx] = max(seg[idx],k);
        return;
    }
    if(qs > e || qe < s){
        return;
    }
    ll mid = (s+e)/2;
    update(s,mid,qs,qe,idx*2,k);
    update(mid+1,e,qs,qe,idx*2+1,k);
    seg[idx] = max(seg[idx*2],seg[idx*2+1]);
}
ll query(ll s,ll e,ll qs,ll qe,ll idx){
    if(qs <= s && e <= qe){
        return seg[idx];
    }
    if(qs > e || qe < s){
        return 0;
    }
    ll mid = (s+e)/2;
    ll a = query(s,mid,qs,qe,idx*2);
    ll b = query(mid+1,e,qs,qe,idx*2+1);
    return max(a,b);
}
int main(void){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    ll n;
    cin>>n;
    ll a[n],b[n];
    map<ll,ll>mp;
    map<ll,ll>pos;
    bool ok1 = 1,ok2 = 1;
    f(i,0,n){
        cin>>a[i];
        pos[a[i]] = i+1;
        if(mp[a[i]] == 1){
            ok1 = 0;
        }
        mp[a[i]]++;
    }
    f(i,0,n){
        cin>>b[i];
        if(b[i] != b[0]){
            ok2 = 0;
        }
        if(ok1){
            b[i] = pos[b[i]];
        }
        if(b[i] == 0){
            b[i] = INF;
        }
    }
    if(ok1){
        ll l[n],r[n];
        priority_queue<ii,vector<ii>,greater<ii> >pq;
        f(i,0,n){
            pq.push(ii(a[i],i));
            while(pq.top().F < a[i]){
                r[pq.top().S] = i-1;
                pq.pop();
            }
        }
        while(!pq.empty()){
            r[pq.top().S] = n-1;
            pq.pop();
        }
        for(ll i=n-1;i >= 0;i--){
            pq.push(ii(a[i],i));
            while(pq.top().F < a[i]){
                l[pq.top().S] = i+1;
                pq.pop();
            }
        }
        while(!pq.empty()){
            l[pq.top().S] = 0;
            pq.pop();
        }
        ll ans = 0;
        ll dp[n+1];
        dp[0] = 0;
        f(i,1,n+1){
            dp[i] = 0;
            if(b[i-1] == INF || !(l[b[i-1]-1] <= i-1 && i-1 <= r[b[i-1]-1])){
                continue;
            }
            dp[i] = query(1,n+1,1,b[i-1],1) + 1;
            update(1,n+1,b[i-1],b[i-1],1,dp[i]);
            ans = max(ans,dp[i]);
        }
        cout<<ans<<endl;
        return 0;
    }
    if(ok2){
        ll ans = 0;
        ll ok = 0;
        ll posa = 0;
        f(i,0,n){
            if(a[i] > b[0]){
                ans += posa * ok;
                ok = 0;
                posa = 0;
            }
            else{
                posa++;
                ok |= (a[i] == b[0]);
            }
        }
        ans += posa * ok;
        cout<<ans<<endl;
        return 0;
    }
    ll l[n],r[n];
    priority_queue<ii,vector<ii>,greater<ii> >pq;
    f(i,0,n){
        pq.push(ii(a[i],i));
        while(pq.top().F < a[i]){
            r[pq.top().S] = i-1;
            pq.pop();
        }
    }
    while(!pq.empty()){
        r[pq.top().S] = n-1;
        pq.pop();
    }
    for(ll i=n-1;i >= 0;i--){
        pq.push(ii(a[i],i));
        while(pq.top().F < a[i]){
            l[pq.top().S] = i+1;
            pq.pop();
        }
    }
    while(!pq.empty()){
        l[pq.top().S] = 0;
        pq.pop();
    }
    ll dp[n+1][n+1];
    f(i,0,n+1){
        f(j,0,n+1){
            if(i == 0 || j == 0){
                dp[i][j] = 0;
            }
            else{
                dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
                if(a[i-1] == b[j-1] && (l[i-1] <= j-1 && j-1 <= r[i-1])){
                    dp[i][j] = max(dp[i][j],dp[i][j-1] + 1);
                }
            }
        }
    }
    cout<<dp[n][n]<<endl;
}

• Subtask 1: 14 / 14
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 23 / 23
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22