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Submission #331982

# Submission time Handle Problem Language Result Execution time Memory
331982 2020-11-30T22:54:33 Z 12tqian Building 4 (JOI20_building4) C++17
100 / 100
 288 ms 45792 KB 
#include <bits/stdc++.h>

int main() {
    using namespace std;
    ios_base::sync_with_stdio(0);
    int n; cin >> n;
    vector<int> a(2 * n), b(2 * n);
    for (int i = 0; i < 2 * n; i++)
        cin >> a[i];
    for (int i = 0; i < 2 * n; i++)
        cin >> b[i];
    // the dp states 
    vector<array<pair<int, int>, 2>> dp(2 * n);
    // 0 stands for A, 1 stands for B
    for (int i = 0; i < 2 * n; i++) 
        for (int j = 0; j < 2; j++) 
            dp[i][j].first = dp[i][j].second = -1;
    dp[0][0] = {1, 1};
    dp[0][1] = {0, 0};
    for (int i = 1; i < 2 * n; i++) {
        // if i end in A
        if (a[i] >= a[i - 1] && dp[i - 1][0].first != -1) {
            dp[i][0] = dp[i - 1][0];
            dp[i][0].first++;
            dp[i][0].second++;
        }
        if (a[i] >= b[i - 1] && dp[i - 1][1].first != -1) {
            if (dp[i][0].first == -1) {
                dp[i][0] = dp[i - 1][1];
                dp[i][0].first++;
                dp[i][0].second++;
            } else {
                dp[i][0].first = min(dp[i][0].first, dp[i - 1][1].first + 1);
                dp[i][0].second = max(dp[i][0].second, dp[i - 1][1].second + 1);
            }
        }
        if (b[i] >= a[i - 1] && dp[i - 1][0].first != -1) {
            dp[i][1] = dp[i - 1][0];
        }
        if (b[i] >= b[i - 1] && dp[i - 1][1].first != -1) {
            if (dp[i][1].first == -1) {
                dp[i][1] = dp[i - 1][1];
            } else { 
                dp[i][1].first = min(dp[i][1].first, dp[i - 1][1].first);
                dp[i][1].second = max(dp[i][1].second, dp[i - 1][1].second);
            }
        }
    }
    auto in = [&](pair<int, int> p, int x) -> bool {
        return p.first <= x && x <= p.second;
    };
    bool ok1 = in(dp[2 * n - 1][0], n);
    bool ok2 = in(dp[2 * n - 1][1], n);
    if (!ok1 && !ok2) {
        cout << -1 << '\n';
    } else {
        int ci = 2 * n - 1, cj, cv = n;
        if (ok1) {
            cj = 0;
        } else { 
            cj = 1;
        }
        string ans = "";
        while (true) {
            ans += (char) ('A' + cj);
            if (ci == 0)
                break;
            if (cj == 0) {
                if (a[ci - 1] <= a[ci] && in(dp[ci - 1][0], cv - 1)) {
                    cj = 0;
                    cv--;
                } else {
                    cj = 1;
                    cv--;
                }
            } else { 
                if (a[ci - 1] <= b[ci] && in(dp[ci - 1][0], cv)) { 
                    cj = 0;
                } else {
                    cj = 1;
                }
            }
            ci--;
        }
        reverse(ans.begin(), ans.end());
        cout << ans << '\n';
    }
    return 0;
}

Subtask #1
11.0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 512 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 384 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 2 ms 492 KB Output is correct
6 Correct 2 ms 492 KB Output is correct
7 Correct 2 ms 492 KB Output is correct
8 Correct 1 ms 492 KB Output is correct
9 Correct 2 ms 492 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 2 ms 492 KB Output is correct
12 Correct 2 ms 512 KB Output is correct
13 Correct 2 ms 492 KB Output is correct
14 Correct 2 ms 492 KB Output is correct
15 Correct 2 ms 492 KB Output is correct
16 Correct 2 ms 492 KB Output is correct
17 Correct 2 ms 492 KB Output is correct
18 Correct 2 ms 492 KB Output is correct
19 Correct 2 ms 492 KB Output is correct
20 Correct 1 ms 492 KB Output is correct
21 Correct 1 ms 512 KB Output is correct
22 Correct 1 ms 492 KB Output is correct
23 Correct 1 ms 492 KB Output is correct
24 Correct 2 ms 512 KB Output is correct
25 Correct 1 ms 492 KB Output is correct
26 Correct 1 ms 492 KB Output is correct
27 Correct 1 ms 492 KB Output is correct
28 Correct 1 ms 492 KB Output is correct
29 Correct 1 ms 492 KB Output is correct
30 Correct 1 ms 492 KB Output is correct
31 Correct 2 ms 492 KB Output is correct
32 Correct 1 ms 492 KB Output is correct
33 Correct 1 ms 492 KB Output is correct

Subtask #2
89.0 / 89.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 512 KB Output is correct
2 Correct 1 ms 364 KB Output is correct
3 Correct 1 ms 384 KB Output is correct
4 Correct 1 ms 364 KB Output is correct
5 Correct 2 ms 492 KB Output is correct
6 Correct 2 ms 492 KB Output is correct
7 Correct 2 ms 492 KB Output is correct
8 Correct 1 ms 492 KB Output is correct
9 Correct 2 ms 492 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 2 ms 492 KB Output is correct
12 Correct 2 ms 512 KB Output is correct
13 Correct 2 ms 492 KB Output is correct
14 Correct 2 ms 492 KB Output is correct
15 Correct 2 ms 492 KB Output is correct
16 Correct 2 ms 492 KB Output is correct
17 Correct 2 ms 492 KB Output is correct
18 Correct 2 ms 492 KB Output is correct
19 Correct 2 ms 492 KB Output is correct
20 Correct 1 ms 492 KB Output is correct
21 Correct 1 ms 512 KB Output is correct
22 Correct 1 ms 492 KB Output is correct
23 Correct 1 ms 492 KB Output is correct
24 Correct 2 ms 512 KB Output is correct
25 Correct 1 ms 492 KB Output is correct
26 Correct 1 ms 492 KB Output is correct
27 Correct 1 ms 492 KB Output is correct
28 Correct 1 ms 492 KB Output is correct
29 Correct 1 ms 492 KB Output is correct
30 Correct 1 ms 492 KB Output is correct
31 Correct 2 ms 492 KB Output is correct
32 Correct 1 ms 492 KB Output is correct
33 Correct 1 ms 492 KB Output is correct
34 Correct 278 ms 42604 KB Output is correct
35 Correct 256 ms 42020 KB Output is correct
36 Correct 251 ms 41380 KB Output is correct
37 Correct 262 ms 42148 KB Output is correct
38 Correct 260 ms 42148 KB Output is correct
39 Correct 246 ms 41380 KB Output is correct
40 Correct 266 ms 44768 KB Output is correct
41 Correct 247 ms 42404 KB Output is correct
42 Correct 265 ms 43812 KB Output is correct
43 Correct 286 ms 45280 KB Output is correct
44 Correct 288 ms 45640 KB Output is correct
45 Correct 281 ms 45536 KB Output is correct
46 Correct 265 ms 45536 KB Output is correct
47 Correct 273 ms 44384 KB Output is correct
48 Correct 261 ms 44164 KB Output is correct
49 Correct 267 ms 45024 KB Output is correct
50 Correct 280 ms 44512 KB Output is correct
51 Correct 282 ms 44640 KB Output is correct
52 Correct 210 ms 33632 KB Output is correct
53 Correct 205 ms 33632 KB Output is correct
54 Correct 187 ms 33648 KB Output is correct
55 Correct 190 ms 33248 KB Output is correct
56 Correct 272 ms 45792 KB Output is correct
57 Correct 230 ms 40288 KB Output is correct
58 Correct 232 ms 40544 KB Output is correct
59 Correct 232 ms 40544 KB Output is correct
60 Correct 224 ms 38564 KB Output is correct
61 Correct 238 ms 41056 KB Output is correct
62 Correct 233 ms 40372 KB Output is correct
63 Correct 236 ms 41056 KB Output is correct
64 Correct 227 ms 39716 KB Output is correct
65 Correct 236 ms 41056 KB Output is correct