oj.uz

Submission #56292

# Submission time Handle Problem Language Result Execution time Memory
56292 2018-07-11T02:32:13 Z model_code Alternating Current (BOI18_alternating) C++17
19 / 100
 76 ms 3468 KB 
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <cassert>

using namespace std;

int 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;
}

int main() {
    ios::sync_with_stdio(0);
    int M;
    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;
    }

    int hi[2] = {0, 0};
    for (int i = 0; i < 2*M; i++) {
        int j = i%M;
        int start = segments[j].start;
        if (i < M) {
            start -= N;
        }
        if (start > hi[0] || start > hi[1]) {
            cout << "IMPOSSIBLE" << endl;
            return 0;
        }
        int end = start + segments[j].length;
        if (hi[0] < hi[1]) {
            segments[j].direction = 0;
        }
        else {
            segments[j].direction = 1;
        }
        hi[segments[j].direction] = max(hi[segments[j].direction], end);
    }
    if (checkSolution(segments)) {
        printSolution(segments);
    }
    else {
        cout << "IMPOSSIBLE" << endl;
    }
}

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 248 KB Output is correct
2 Correct 2 ms 484 KB Output is correct
3 Correct 4 ms 484 KB Output is correct
4 Incorrect 2 ms 484 KB 'impossible' claimed, but there is a solution
5 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 588 KB Output is correct
2 Incorrect 2 ms 588 KB 'impossible' claimed, but there is a solution
3 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 588 KB Output is correct
2 Incorrect 3 ms 588 KB 'impossible' claimed, but there is a solution
3 Halted 0 ms 0 KB -

Subtask #4
19.0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 69 ms 3220 KB Output is correct
2 Correct 3 ms 3220 KB Output is correct
3 Correct 21 ms 3220 KB Output is correct
4 Correct 30 ms 3220 KB Output is correct
5 Correct 67 ms 3316 KB Output is correct
6 Correct 68 ms 3328 KB Output is correct
7 Correct 71 ms 3376 KB Output is correct
8 Correct 5 ms 3376 KB Output is correct
9 Correct 3 ms 3376 KB Output is correct
10 Correct 72 ms 3376 KB Output is correct
11 Correct 48 ms 3376 KB Output is correct
12 Correct 73 ms 3376 KB Output is correct
13 Correct 3 ms 3376 KB Output is correct
14 Correct 9 ms 3376 KB Output is correct
15 Correct 71 ms 3376 KB Output is correct
16 Correct 30 ms 3376 KB Output is correct
17 Correct 76 ms 3468 KB Output is correct
18 Correct 76 ms 3468 KB Output is correct
19 Correct 6 ms 3468 KB Output is correct
20 Correct 67 ms 3468 KB Output is correct

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Incorrect 3 ms 3468 KB 'impossible' claimed, but there is a solution
2 Halted 0 ms 0 KB -