oj.uz

Submission #877439

# Submission time Handle Problem Language Result Execution time Memory
877439 2023-11-23T08:39:22 Z danikoynov Building 4 (JOI20_building4) C++14
100 / 100
 835 ms 83820 KB 
#include<bits/stdc++.h>

#define endl '\n'

using namespace std;
typedef long long ll;

const int maxn = 1e6 + 10;

int n, l[maxn][2];
void input()
{
    cin >> n;
    n *= 2;
    for (int i = 1; i <= n; i ++)
        cin >> l[i][0];
    for (int i = 1; i <= n; i ++)
        cin >> l[i][1];
}


int dp[maxn][2], from[maxn][2];
string get_max(int c)
{
    for (int i = 1; i <= n; i ++)
    {
        dp[i][0] = dp[i][1] = -1e9;
        from[i][0] = from[i][1] = -1;
    }

    dp[1][c] = 1;
    dp[1][(1 + c) % 2] = 0;

    ///cout << "--------------" << endl;
    for (int i = 2; i <= n; i ++)
    {
        for (int t = 0; t < 2; t ++)
            for (int d = 0; d < 2; d ++)
            {
                if (l[i - 1][t] <= l[i][d])
                {
                    int val = dp[i - 1][t] + (d == c);
                    if (val > dp[i][d])
                    {
                        from[i][d] = t;
                        dp[i][d] = val;
                    }
                }
            }

        ///cout << dp[i][0] << " " << dp[i][1] << endl;
    }

    string res = "";
    if (dp[n][0] < 0 && dp[n][1] < 0)
        return res;

    int row = n, state = 0;
    if (dp[n][1] > dp[n][0])
        state = 1;


    while(row > 1)
    {
        ///cout << state << endl;
        int val = l[row][state];
        int bef = l[row - 1][from[row][state]];
        assert(bef <= val);
        if (state == 0)
            res.push_back('A');
        else
            res.push_back('B');

        state = from[row][state];
        row --;
    }

    if (state == 0)
        res.push_back('A');
    else
        res.push_back('B');

    reverse(res.begin(), res.end());

    return res;
}

bool can_swap(string &a, int &b, int pos)
{


    int val = l[pos + 1][0];
    if (a[pos] == 'A')
        val = l[pos + 1][1];
    if (pos > 0)
    {
        int bef = l[pos][0];
        if (a[pos - 1] == 'B')
            bef = l[pos][1];
        if (bef > val)
            return false;
    }

    if (pos + 1 < a.size())
    {
        int nxt = l[pos + 2][0];
        if (a[pos + 1] == 'B')
            nxt = l[pos + 2][1];
        if (nxt < val)
            return false;
    }


    if (a[pos] == 'A')
    {
        a[pos] = 'B';
        b -= 2;
    }
    else
    {
        a[pos] = 'A';
        b += 2;
    }

    return true;
}

bool can_change(int pos, string &a)
{
    int val = l[pos + 1][0];
    if (a[pos] == 'A')
        val = l[pos + 1][1];

    if (pos > 0)
    {
        int bef = l[pos][0];
        if (a[pos - 1] == 'B')
            bef = l[pos][1];
        if (bef > val)
            return false;
    }

    if (pos + 1 < a.size())
    {
        int nxt = l[pos + 2][0];
        if (a[pos + 1] == 'B')
            nxt = l[pos + 2][1];
        if (nxt < val)
            return false;
    }

    return true;
}

set < int > act;

void check_to_change(int pos, string &a, string &b)
{
    if (pos < 0 || pos == n)
        return;

    if (a[pos] == b[pos])
        return;

    if (can_change(pos, a))
    {
        act.insert(pos);
    }
    else
    {
        if (act.find(pos) != act.end())
            act.erase(pos);
    }
}
void simulate()
{
    string a = get_max(0);
    string b = get_max(1);

    if (a.empty() || b.empty())
    {
        cout << -1 << endl;
        return;
    }

    int balance = 0;
    for (int i = 0; i < a.size(); i ++)
    {
        if (a[i] == 'A')
            balance ++;
        else
            balance --;
    }
    /***/

    int bl = 0;
    for (int i = 0; i < b.size(); i ++)
    {
        if (b[i] == 'A')
            bl ++;
        else
            bl --;
    }

    assert(balance % 2 == 0 && bl % 2 == 0);

    for (int i = 0; i < n; i ++)
        check_to_change(i, a, b);
    while(balance != 0)
    {
        if (act.empty())
            break;

        int val = *act.begin();
        act.erase(val);
        assert(can_swap(a, balance, val));
        check_to_change(val - 1, a, b);
        check_to_change(val, a, b);
        check_to_change(val + 1, a, b);
    }
    ///int lf = 0, rf = (int)(a.size()) - 1;



    if (balance != 0)
        cout << -1 << endl;
    else
    {
        assert(n == a.size());
        int cnt = 0, cnt2 = 0;
        for (int i = 0; i < n; i ++)
            if (a[i] == 'A')
                cnt ++;
            else
            if (a[i] == 'B')
                cnt2 ++;
        assert(cnt == n / 2 && cnt2 == n / 2);
        for (int i = 1; i < n; i ++)
        {
            int val = l[i + 1][0];
            if (a[i] == 'B')
                val = l[i + 1][1];
            int bef = l[i][0];
            if (a[i - 1] == 'B')
                bef = l[i][1];
            assert(bef <= val);
        }
        cout << a << endl;
    }
}
void solve()
{
    input();
    simulate();
}
int main()
{
    solve();
    return 0;
}

Compilation message

building4.cpp: In function 'bool can_swap(std::string&, int&, int)':
building4.cpp:104:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  104 |     if (pos + 1 < a.size())
      |         ~~~~~~~~^~~~~~~~~~
building4.cpp: In function 'bool can_change(int, std::string&)':
building4.cpp:143:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  143 |     if (pos + 1 < a.size())
      |         ~~~~~~~~^~~~~~~~~~
building4.cpp: In function 'void simulate()':
building4.cpp:187:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  187 |     for (int i = 0; i < a.size(); i ++)
      |                     ~~^~~~~~~~~~
building4.cpp:197:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  197 |     for (int i = 0; i < b.size(); i ++)
      |                     ~~^~~~~~~~~~
In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from building4.cpp:1:
building4.cpp:229:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  229 |         assert(n == a.size());
      |                ~~^~~~~~~~~~~

Subtask #1
11.0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 4444 KB Output is correct
2 Correct 1 ms 4444 KB Output is correct
3 Correct 1 ms 4444 KB Output is correct
4 Correct 1 ms 4440 KB Output is correct
5 Correct 3 ms 4444 KB Output is correct
6 Correct 3 ms 4544 KB Output is correct
7 Correct 3 ms 4444 KB Output is correct
8 Correct 5 ms 4700 KB Output is correct
9 Correct 3 ms 4552 KB Output is correct
10 Correct 3 ms 4444 KB Output is correct
11 Correct 3 ms 4444 KB Output is correct
12 Correct 3 ms 4440 KB Output is correct
13 Correct 4 ms 4444 KB Output is correct
14 Correct 4 ms 4952 KB Output is correct
15 Correct 3 ms 4700 KB Output is correct
16 Correct 3 ms 4700 KB Output is correct
17 Correct 5 ms 4708 KB Output is correct
18 Correct 3 ms 4444 KB Output is correct
19 Correct 3 ms 4444 KB Output is correct
20 Correct 2 ms 4444 KB Output is correct
21 Correct 2 ms 4444 KB Output is correct
22 Correct 3 ms 4700 KB Output is correct
23 Correct 2 ms 4700 KB Output is correct
24 Correct 3 ms 4444 KB Output is correct
25 Correct 2 ms 4444 KB Output is correct
26 Correct 3 ms 4444 KB Output is correct
27 Correct 2 ms 4444 KB Output is correct
28 Correct 2 ms 4444 KB Output is correct
29 Correct 2 ms 4696 KB Output is correct
30 Correct 2 ms 4444 KB Output is correct
31 Correct 3 ms 4444 KB Output is correct
32 Correct 2 ms 4444 KB Output is correct
33 Correct 2 ms 4444 KB Output is correct

Subtask #2
89.0 / 89.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 4444 KB Output is correct
2 Correct 1 ms 4444 KB Output is correct
3 Correct 1 ms 4444 KB Output is correct
4 Correct 1 ms 4440 KB Output is correct
5 Correct 3 ms 4444 KB Output is correct
6 Correct 3 ms 4544 KB Output is correct
7 Correct 3 ms 4444 KB Output is correct
8 Correct 5 ms 4700 KB Output is correct
9 Correct 3 ms 4552 KB Output is correct
10 Correct 3 ms 4444 KB Output is correct
11 Correct 3 ms 4444 KB Output is correct
12 Correct 3 ms 4440 KB Output is correct
13 Correct 4 ms 4444 KB Output is correct
14 Correct 4 ms 4952 KB Output is correct
15 Correct 3 ms 4700 KB Output is correct
16 Correct 3 ms 4700 KB Output is correct
17 Correct 5 ms 4708 KB Output is correct
18 Correct 3 ms 4444 KB Output is correct
19 Correct 3 ms 4444 KB Output is correct
20 Correct 2 ms 4444 KB Output is correct
21 Correct 2 ms 4444 KB Output is correct
22 Correct 3 ms 4700 KB Output is correct
23 Correct 2 ms 4700 KB Output is correct
24 Correct 3 ms 4444 KB Output is correct
25 Correct 2 ms 4444 KB Output is correct
26 Correct 3 ms 4444 KB Output is correct
27 Correct 2 ms 4444 KB Output is correct
28 Correct 2 ms 4444 KB Output is correct
29 Correct 2 ms 4696 KB Output is correct
30 Correct 2 ms 4444 KB Output is correct
31 Correct 3 ms 4444 KB Output is correct
32 Correct 2 ms 4444 KB Output is correct
33 Correct 2 ms 4444 KB Output is correct
34 Correct 568 ms 33368 KB Output is correct
35 Correct 561 ms 35272 KB Output is correct
36 Correct 552 ms 34760 KB Output is correct
37 Correct 568 ms 35264 KB Output is correct
38 Correct 766 ms 78536 KB Output is correct
39 Correct 596 ms 45884 KB Output is correct
40 Correct 673 ms 49688 KB Output is correct
41 Correct 551 ms 35276 KB Output is correct
42 Correct 579 ms 36036 KB Output is correct
43 Correct 627 ms 37640 KB Output is correct
44 Correct 611 ms 37700 KB Output is correct
45 Correct 613 ms 37752 KB Output is correct
46 Correct 835 ms 83820 KB Output is correct
47 Correct 626 ms 48152 KB Output is correct
48 Correct 637 ms 48000 KB Output is correct
49 Correct 669 ms 49796 KB Output is correct
50 Correct 593 ms 37052 KB Output is correct
51 Correct 603 ms 37244 KB Output is correct
52 Correct 361 ms 31880 KB Output is correct
53 Correct 353 ms 31812 KB Output is correct
54 Correct 600 ms 77272 KB Output is correct
55 Correct 534 ms 65848 KB Output is correct
56 Correct 643 ms 37760 KB Output is correct
57 Correct 511 ms 35144 KB Output is correct
58 Correct 542 ms 35136 KB Output is correct
59 Correct 503 ms 35200 KB Output is correct
60 Correct 482 ms 40392 KB Output is correct
61 Correct 503 ms 42824 KB Output is correct
62 Correct 495 ms 42396 KB Output is correct
63 Correct 538 ms 42760 KB Output is correct
64 Correct 487 ms 41108 KB Output is correct
65 Correct 517 ms 42652 KB Output is correct