Submission #1205240

#	Time	Username	Problem	Language	Result	Execution time	Memory
1205240		andrei_n	Exam (eJOI20_exam)	C++20	65 / 100	175 ms	98976 KiB

exam

#include <bits/stdc++.h>

using namespace std;

int a[100005], b[100005];
map<int,int> pos;
int aib[100005];
int dp[5005][5005];
int rmq[17][100005];
int e[100005];
int n;

void updateAIB(int p, int x)
{
    p = n + 2 - p;
    for(; p<=n+3; p+=(p&-p))
        aib[p] += x;
}

int queryAIB(int p)
{
    p = n + 2 - p;
    int res = 0;
    for(; p; p^=(p&-p))
        res += aib[p];
    return res;
}

inline int query(const int &a, const int &b)
{
    return max(rmq[e[b-a+1]][a], rmq[e[b-a+1]][b + 1 - (1<<e[b-a+1])]);
}

signed main()
{
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    cin>>n;
    for(int i=1; i<=n; ++i)
    {
        cin>>a[i];
        rmq[0][i] = a[i];
        pos[a[i]] = i;
    }
    for(int i=1; i<=n; ++i) cin>>b[i];
    for(int i=1; i<17; ++i)
        for(int j=1; j+(1<<i)-1 <= n; ++j)
            rmq[i][j] = max(rmq[i-1][j], rmq[i-1][j+(1<<i-1)]);
    for(int i=2; i<=n; ++i)
        e[i] = e[i-1] + ((i & (i-1)) == 0);
    if(n <= 5000)
    {
        for(int i=1; i<=n; ++i)
        {
            for(int j=1; j<=n; ++j)
            {
                dp[i][j] = dp[i][j-1];
                if(a[j] == query(min(i,j), max(i,j)))
                    dp[i][j] = max(dp[i][j], dp[i-1][j] + (a[j] == b[i]));
            }
        }
        cout<<dp[n][n];
    }
    else
    {
        for(int i=1; i<=n; ++i)
        {
            int j = pos[b[i]];
            if(!j) continue;
            if(a[j] != query(min(i,j), max(i,j)))
                continue;
            updateAIB(n, 1);
            updateAIB(j-1, -1);
        }
        cout<<queryAIB(n);
    }
    return 0;
}

• Subtask 1: 14 / 14
• Subtask 2: 0 / 12
• Subtask 3: 13 / 13
• Subtask 4: 0 / 23
• Subtask 5: 16 / 16
• Subtask 6: 22 / 22