Submission #56289

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
56289	2018-07-11T02:29:29 Z	model_code	Alternating Current (BOI18_alternating)	C++17	100 / 100	256 ms	64220 KB

alternating

// This solution has not been proven correct, so it may not be.
// However, it has been tested on a large number of random test cases.
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <cassert>

using namespace std;

int M, N;

struct Segment {
    int index, sortedIndex;
    int start, length;
    bool direction;

    Segment(int index, int start, int length) : 
        index(index),
        start(start), 
        length(length), 
        direction(0) {
    }

    // Check if this segment is completely inside another segment
    bool isSubsetOf(const Segment& other) const {
        int relativeStart = (start - other.start + N) % N;
        return relativeStart + length <= other.length;
    }
};

// Returns whether the given solution covers the whole circle
bool checkSolution(const vector<Segment>& segments) {
    for (int direction = 0; direction < 2; direction++) {
        size_t n = segments.size();
        int hi = 0;
        for (size_t i = 0; i < 2*n; i++) {
            size_t j = i%n;
            if (segments[j].direction != direction) {
                continue;
            }
            int start = segments[j].start;
            if (i < n) {
                start -= N;
            }
            if (start > hi) {
                return false;
            }
            int end = start + segments[j].length;
            hi = max(hi, end);
        }
        if (hi < N) {
            return false;
        }
    }
    return true;
}

void printSolution(const vector<Segment>& segments) {
    vector<bool> directions(segments.size());
    for (const Segment& segment : segments) {
        directions[segment.index] = segment.direction;
    }
    for (bool d : directions) {
        cout << d;
    }
    cout << endl;
}

set<pair<int, pair<int, pair<int, int> > > > checked;

void rec(vector<Segment>& segments, int i, int hi0, int hi1, int inRow) {
    if (i == 2*M) {
        if (checkSolution(segments)) {
            printSolution(segments);
            exit(0);
        }
        return;
    }
    auto key = make_pair(inRow, make_pair(i, make_pair(hi0, hi1)));
    if (checked.count(key))
        return;
    checked.insert(key);
    int j = i%M;
    int start = segments[j].start;
    if (i < M) {
        start -= N;
    }
    if (start > hi0 || start > hi1) {
        return;
    }
    int end = start + segments[j].length;
    if (end > hi1 || end <= hi0) {
        int newInRow = inRow;
        if (hi1 > hi0) {
            ++newInRow;
        }
        else {
            newInRow = 0;
        }
        if (newInRow < 2) {
            segments[j].direction = 1;
            rec(segments, i+1, hi0, max(hi1, end), newInRow);
        }
    }
    if (end > hi0 || end <= hi1) {
        int newInRow = inRow;
        if (hi0 > hi1) {
            ++newInRow;
        }
        else {
            newInRow = 0;
        }
        if (newInRow < 2) {
            segments[j].direction = 0;
            rec(segments, i+1, max(hi0, end), hi1, newInRow);
        }
    }
}

int main() {
    ios::sync_with_stdio(0);
    cin >> N >> M;

    vector<Segment> segments;
    for (int i = 0; i < M; i++) {
        int a, b;
        cin >> a >> b;
        segments.emplace_back(i, a-1, ((b-a+N)%N)+1);
    }

    sort(segments.begin(), segments.end(), [](const Segment& a, const Segment& b) -> bool {
        if (a.start == b.start) {
            return a.length > b.length;
        }
        return a.start < b.start;
    });

    for (int i = 0; i < M; i++) {
        segments[i].sortedIndex = i;
    }

    rec(segments, 0, 0, 0, 0);
    cout << "IMPOSSIBLE" << endl;
}

Subtask #1
13.0 / 13.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	2 ms	248 KB	Output is correct
2	Correct	2 ms	360 KB	Output is correct
3	Correct	2 ms	472 KB	Output is correct
4	Correct	3 ms	584 KB	Output is correct
5	Correct	2 ms	696 KB	Output is correct
6	Correct	2 ms	828 KB	Output is correct
7	Correct	2 ms	828 KB	Output is correct
8	Correct	2 ms	828 KB	Output is correct
9	Correct	3 ms	828 KB	Output is correct
10	Correct	2 ms	828 KB	Output is correct
11	Correct	2 ms	828 KB	Output is correct
12	Correct	2 ms	828 KB	Output is correct
13	Correct	3 ms	828 KB	Output is correct
14	Correct	3 ms	828 KB	Output is correct
15	Correct	3 ms	828 KB	Output is correct
16	Correct	3 ms	828 KB	Output is correct
17	Correct	3 ms	828 KB	Output is correct
18	Correct	3 ms	828 KB	Output is correct
19	Correct	3 ms	828 KB	Output is correct
20	Correct	3 ms	828 KB	Output is correct
21	Correct	2 ms	828 KB	Output is correct
22	Correct	2 ms	828 KB	Output is correct
23	Correct	2 ms	828 KB	Output is correct
24	Correct	2 ms	828 KB	Output is correct
25	Correct	3 ms	932 KB	Output is correct
26	Correct	2 ms	932 KB	Output is correct
27	Correct	2 ms	932 KB	Output is correct
28	Correct	2 ms	932 KB	Output is correct
29	Correct	2 ms	976 KB	Output is correct
30	Correct	3 ms	976 KB	Output is correct
31	Correct	2 ms	976 KB	Output is correct
32	Correct	2 ms	976 KB	Output is correct
33	Correct	2 ms	992 KB	Output is correct
34	Correct	2 ms	992 KB	Output is correct
35	Correct	3 ms	992 KB	Output is correct
36	Correct	2 ms	992 KB	Output is correct
37	Correct	4 ms	992 KB	Output is correct
38	Correct	3 ms	992 KB	Output is correct
39	Correct	2 ms	992 KB	Output is correct
40	Correct	2 ms	992 KB	Output is correct

Subtask #2
20.0 / 20.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	992 KB	Output is correct
2	Correct	2 ms	992 KB	Output is correct
3	Correct	2 ms	992 KB	Output is correct
4	Correct	3 ms	992 KB	Output is correct
5	Correct	2 ms	992 KB	Output is correct
6	Correct	0 ms	992 KB	Output is correct
7	Correct	2 ms	992 KB	Output is correct
8	Correct	2 ms	1048 KB	Output is correct
9	Correct	2 ms	1048 KB	Output is correct
10	Correct	2 ms	1048 KB	Output is correct
11	Correct	2 ms	1048 KB	Output is correct
12	Correct	2 ms	1048 KB	Output is correct
13	Correct	2 ms	1048 KB	Output is correct
14	Correct	2 ms	1048 KB	Output is correct
15	Correct	2 ms	1048 KB	Output is correct
16	Correct	3 ms	1048 KB	Output is correct
17	Correct	2 ms	1048 KB	Output is correct
18	Correct	3 ms	1096 KB	Output is correct
19	Correct	2 ms	1096 KB	Output is correct
20	Correct	2 ms	1096 KB	Output is correct
21	Correct	3 ms	1096 KB	Output is correct
22	Correct	3 ms	1096 KB	Output is correct
23	Correct	2 ms	1096 KB	Output is correct
24	Correct	3 ms	1096 KB	Output is correct
25	Correct	3 ms	1096 KB	Output is correct
26	Correct	2 ms	1096 KB	Output is correct
27	Correct	2 ms	1116 KB	Output is correct
28	Correct	3 ms	1120 KB	Output is correct
29	Correct	2 ms	1120 KB	Output is correct

Subtask #3
22.0 / 22.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	3 ms	1304 KB	Output is correct
2	Correct	4 ms	1444 KB	Output is correct
3	Correct	3 ms	1444 KB	Output is correct
4	Correct	3 ms	1444 KB	Output is correct
5	Correct	3 ms	1444 KB	Output is correct
6	Correct	3 ms	1444 KB	Output is correct
7	Correct	3 ms	1444 KB	Output is correct
8	Correct	3 ms	1444 KB	Output is correct
9	Correct	3 ms	1444 KB	Output is correct
10	Correct	3 ms	1444 KB	Output is correct
11	Correct	3 ms	1444 KB	Output is correct
12	Correct	2 ms	1444 KB	Output is correct
13	Correct	3 ms	1444 KB	Output is correct
14	Correct	3 ms	1444 KB	Output is correct
15	Correct	3 ms	1536 KB	Output is correct
16	Correct	3 ms	1536 KB	Output is correct
17	Correct	5 ms	1536 KB	Output is correct
18	Correct	3 ms	1548 KB	Output is correct
19	Correct	3 ms	1548 KB	Output is correct
20	Correct	4 ms	1548 KB	Output is correct
21	Correct	4 ms	1548 KB	Output is correct
22	Correct	3 ms	1548 KB	Output is correct
23	Correct	4 ms	1548 KB	Output is correct
24	Correct	2 ms	1548 KB	Output is correct
25	Correct	3 ms	1548 KB	Output is correct
26	Correct	2 ms	1548 KB	Output is correct
27	Correct	4 ms	1640 KB	Output is correct
28	Correct	4 ms	1640 KB	Output is correct
29	Correct	4 ms	1640 KB	Output is correct

Subtask #4
19.0 / 19.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	204 ms	38652 KB	Output is correct
2	Correct	3 ms	38652 KB	Output is correct
3	Correct	67 ms	38652 KB	Output is correct
4	Correct	94 ms	38652 KB	Output is correct
5	Correct	166 ms	39936 KB	Output is correct
6	Correct	188 ms	39936 KB	Output is correct
7	Correct	165 ms	39936 KB	Output is correct
8	Correct	7 ms	39936 KB	Output is correct
9	Correct	3 ms	39936 KB	Output is correct
10	Correct	161 ms	45000 KB	Output is correct
11	Correct	134 ms	45000 KB	Output is correct
12	Correct	224 ms	45000 KB	Output is correct
13	Correct	2 ms	45000 KB	Output is correct
14	Correct	2 ms	45000 KB	Output is correct
15	Correct	192 ms	47340 KB	Output is correct
16	Correct	170 ms	47340 KB	Output is correct
17	Correct	167 ms	49096 KB	Output is correct
18	Correct	187 ms	50252 KB	Output is correct
19	Correct	10 ms	50252 KB	Output is correct
20	Correct	220 ms	51252 KB	Output is correct

Subtask #5
26.0 / 26.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	2 ms	51252 KB	Output is correct
2	Correct	189 ms	51252 KB	Output is correct
3	Correct	98 ms	51252 KB	Output is correct
4	Correct	3 ms	51252 KB	Output is correct
5	Correct	7 ms	51252 KB	Output is correct
6	Correct	58 ms	51252 KB	Output is correct
7	Correct	43 ms	51252 KB	Output is correct
8	Correct	0 ms	51252 KB	Output is correct
9	Correct	16 ms	51252 KB	Output is correct
10	Correct	165 ms	51252 KB	Output is correct
11	Correct	81 ms	51252 KB	Output is correct
12	Correct	101 ms	51252 KB	Output is correct
13	Correct	3 ms	51252 KB	Output is correct
14	Correct	5 ms	51252 KB	Output is correct
15	Correct	156 ms	56776 KB	Output is correct
16	Correct	45 ms	56776 KB	Output is correct
17	Correct	3 ms	56776 KB	Output is correct
18	Correct	90 ms	56776 KB	Output is correct
19	Correct	256 ms	64220 KB	Output is correct
20	Correct	3 ms	64220 KB	Output is correct

Submission #56289

Compilation message

Subtask #1 13.0 / 13.0

Subtask #2 20.0 / 20.0

Subtask #3 22.0 / 22.0

Subtask #4 19.0 / 19.0

Subtask #5 26.0 / 26.0

Subtask #1
13.0 / 13.0

Subtask #2
20.0 / 20.0

Subtask #3
22.0 / 22.0

Subtask #4
19.0 / 19.0

Subtask #5
26.0 / 26.0