Submission #1127396

#	Time	Username	Problem	Language	Result	Execution time	Memory
1127396		khanhphucscratch	Exam (eJOI20_exam)	C++20	0 / 100	906 ms	98268 KiB

exam

//n <= 5000, subtask 1, 3, 5, 6
#include<bits/stdc++.h>
using namespace std;
int dp[5005][5005], a[5005], b[5005];
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n; cin>>n;
    for(int i = 1; i <= n; i++) cin>>a[i];
    for(int i = 1; i <= n; i++) cin>>b[i];
    int curmaxa = 0;
    for(int i = 1; i <= n; i++){
        curmaxa = max(curmaxa, a[i]);
        if(a[i] == curmaxa) dp[0][i] = 0;
        else dp[0][i] = -1e9;
    }
    for(int i = 1; i <= n; i++){
        //Previous is current max of now
        stack<int> value_stack, dp_stack;
        for(int j = 1; j <= n; j++){
            while(value_stack.size() > 0 && a[value_stack.top()] < a[j]){
                int x = value_stack.top(); value_stack.pop();
                //Update dp stack
                if(dp_stack.size() > 0 && dp_stack.top() == x) dp_stack.pop();
            }
            value_stack.push(j);
            if(dp_stack.size() == 0 || dp[i-1][dp_stack.top()] < dp[i-1][j]) dp_stack.push(j);
            dp[i][j] = max(dp[i][j], dp[i-1][dp_stack.top()]);
        }
        //Now is the current max of previous
        stack<pair<int, int>> dp_val_stack;
        for(int j = 1; j <= n; j++){
            int curmax = dp[i-1][j];
            while(dp_val_stack.size() > 0 && a[dp_val_stack.top().first] <= a[j]){
                curmax = max(curmax, dp_val_stack.top().second);
                dp_val_stack.pop();
            }
            dp_val_stack.push({j, curmax});
            dp[i][j] = max(dp[i][j], curmax);
        }
        //Update b
        for(int j = 1; j <= n; j++) if(b[i] == a[j]) dp[i][j]++;
        //for(int j = 1; j <= n; j++) cout<<i<<" "<<j<<" "<<dp[i][j]<<endl;
    }
    int ans = 0, curmax = 0;
    for(int i = n; i >= 1; i--){
        curmax = max(curmax, a[i]);
        if(a[i] == curmax) ans = max(ans, dp[n][i]);
    }
    cout<<ans;
}

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