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답안 #1044160

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
1044160 2024-08-05T07:42:10 Z 우민규(#11006) Parking (CEOI22_parking) C++17
50 / 100
 189 ms 32452 KB 
#include <bits/stdc++.h>
using namespace std;

int n, m;
vector<int> fst, snd;
// bottom -> up then true, up -> bottom then false
vector<vector<int>> adj;
vector<int> type;
// determine type

vector<bool> visited, is_selfloop;
vector<vector<int>> locs;

enum Component {
    TrivialPath,
    SplitPath,
    PerfectCycle,
    SplitCycle,
    ComplexCycle,
    SelfLoop,
    EmptySelfLoop,
};

// {amt of top, saw path}
pair<int, bool> dfs(int node) {
    visited[node] = true;
    int top_amt = type[node] == 3;
    bool is_path = false;
    for (auto v : adj[node]) {
        if (visited[v]) continue;
        if (v == 0) {
            is_path = true;
        } else {
            auto [tt, ip] = dfs(v);
            top_amt += tt;
            is_path |= ip;
        }
    }
    return {top_amt, is_path};
}

Component component_type(int node) {
    if (is_selfloop[node]) return SelfLoop;

    auto [top_amt, is_path] = dfs(node);
    if (is_path) {
        if (top_amt) return SplitPath;
        return TrivialPath;
    }
    if (top_amt > 1) return ComplexCycle;
    if (top_amt) return SplitCycle;
    return PerfectCycle;
}

vector<pair<int, int>> drives;

vector<int> auxs;

void trivial_contraction(int node) {
    if (node == 0 || type[node] == 3) return;
    int a = locs[node][0];
    int b = locs[node][1];
    if (a == b) return;
    bool can_a_pop = snd[a] == 0 || snd[a] == node;
    bool can_b_pop = snd[b] == 0 || snd[b] == node;
    bool can_a_recv = fst[a] == node && snd[a] == 0;
    bool can_b_recv = fst[b] == node && snd[b] == 0;
    if (can_b_pop && can_a_recv) {
        drives.push_back({b, a});
        fst[a] = snd[a] = node;
        locs[node] = {a, a};
        if (snd[b] == node) {
            snd[b] = 0;
            trivial_contraction(fst[b]);
        } else {
            fst[b] = 0;
            auxs.push_back(b);
        }
    } else if (can_a_pop && can_b_recv) {
        drives.push_back({a, b});
        fst[b] = snd[b] = node;
        locs[node] = {b, b};
        if (snd[a] == node) {
            snd[a] = 0;
            trivial_contraction(fst[a]);
        } else {
            fst[a] = 0;
            auxs.push_back(a);
        }
    }
}

void trivial_component_contraction(int node) {
    visited[node] = true;
    trivial_contraction(node);
    for (auto v : adj[node]) {
        if (visited[v]) continue;
        trivial_component_contraction(v);
    }
}

void perfect_cycle_contraction(int node) {
    assert(!auxs.empty());
    int aux = auxs.back();
    auxs.pop_back();
    
    int a = locs[node][0], b = locs[node][1];
    if (snd[a] == node) {
        drives.push_back({a, aux});
        snd[a] = 0;
        fst[aux] = node;
        locs[node][0] = aux;
        trivial_contraction(fst[a]);
    }
    if (snd[b] == node) {
        drives.push_back({b, aux});
        snd[b] = 0;
        fst[aux] = node;
        locs[node][1] = aux;
        trivial_contraction(fst[b]);
    }
}

vector<int> component_top_nodes;
void find_top_node_and_contract_ends(int node) {
    visited[node] = true;
    if (type[node] == 3) component_top_nodes.push_back(node);
    trivial_contraction(node);
    for (auto v : adj[node]) if (!visited[v]) find_top_node_and_contract_ends(v);
}

void with_top_contraction(int node) {
    component_top_nodes.clear();
    find_top_node_and_contract_ends(node);
    for (auto v : component_top_nodes) {
        assert(!auxs.empty());
        int aux = auxs.back();
        auxs.pop_back();

        int a = locs[v][0];
        int b = locs[v][1];
        locs[v][0] = locs[v][1] = aux;

        drives.push_back({a, aux});
        drives.push_back({b, aux});
        snd[a] = 0, snd[b] = 0;
        trivial_contraction(fst[a]);
        trivial_contraction(fst[b]);
    }
}


void solve() {
    cin >> n >> m;
    adj.assign(n + 1, {}), type.assign(n + 1, 0), visited.assign(n + 1, false), is_selfloop.assign(n + 1, false);
    locs.assign(n + 1, {});
    int num_type[7]{};
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        if (a) type[a] = 2 * type[a];
        if (b) type[b] = 2 * type[b] + 1;
        fst.push_back(a), snd.push_back(b);
        adj[a].push_back(b), adj[b].push_back(a);
        locs[a].push_back(i), locs[b].push_back(i);
        if (a == 0 && b == 0) {
            num_type[EmptySelfLoop] += 1;
            auxs.push_back(i);
        }
        if (a == b) {
            is_selfloop[a] = true;
        }
    }
    // determine all endpoints
    vector<pair<Component, int>> sources;
    for (int i = 1; i <= n; ++i) {
        if (!visited[i]) {
            Component cur = component_type(i);
            num_type[cur] += 1;
            sources.push_back({cur, i});
        }
    }

    int req_moves = num_type[PerfectCycle];
    for (int i = 1; i <= n; ++i) {
        if (is_selfloop[i]) continue;
        req_moves += 1;
        if (type[i] == 3) req_moves += 1;
    }

    // Check if it's possible
    num_type[EmptySelfLoop] += num_type[TrivialPath];
    num_type[TrivialPath] = 0;
    if (num_type[EmptySelfLoop] == 0 &&
        (num_type[SplitPath] > 0 || num_type[PerfectCycle] > 0 ||
         num_type[SplitCycle] > 0 || num_type[ComplexCycle] > 0)) {
        cout << "-1\n";
        return;
    }
    num_type[EmptySelfLoop] += num_type[SplitPath];
    if (num_type[ComplexCycle] > 0) {
        if (num_type[EmptySelfLoop] < 2) {
            cout << "-1\n";
            return;
        }
    }
    // do the thing
    visited.assign(n + 1, false);
    for (auto [type, idx] : sources) {
        if (type == TrivialPath) trivial_component_contraction(idx);
    }
    for (auto [type, idx] : sources) {
        if (type == SplitPath || type == SplitCycle) with_top_contraction(idx);
        if (type == PerfectCycle) perfect_cycle_contraction(idx);
    }
    for (auto [type, idx] : sources) {
        if (type == ComplexCycle) with_top_contraction(idx);
    }
    assert(req_moves == drives.size());
    cout << drives.size() << "\n";
    for (auto [u, v] : drives) cout << u + 1 << " " << v + 1 << "\n";
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
    solve();
}

Compilation message

In file included from /usr/include/c++/10/cassert:44,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:33,
                 from Main.cpp:1:
Main.cpp: In function 'void solve()':
Main.cpp:219:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  219 |     assert(req_moves == drives.size());
      |            ~~~~~~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:226:9: warning: unused variable 't' [-Wunused-variable]
  226 |     int t = 1;
      |         ^

Subtask #1
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 364 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 604 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 1 ms 344 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct

Subtask #2
0.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 52 ms 30336 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #3
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 1 ms 460 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 348 KB Output is correct
6 Correct 1 ms 348 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 1 ms 604 KB Output is correct

Subtask #4
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 344 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 1 ms 460 KB Output is correct
4 Correct 1 ms 604 KB Output is correct
5 Correct 1 ms 348 KB Output is correct
6 Correct 1 ms 348 KB Output is correct
7 Correct 1 ms 604 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 1 ms 604 KB Output is correct
10 Correct 189 ms 32328 KB Output is correct
11 Correct 61 ms 28612 KB Output is correct
12 Correct 75 ms 26424 KB Output is correct
13 Correct 136 ms 30908 KB Output is correct
14 Correct 80 ms 27204 KB Output is correct
15 Correct 87 ms 26276 KB Output is correct
16 Correct 158 ms 32452 KB Output is correct
17 Correct 77 ms 25920 KB Output is correct
18 Correct 123 ms 31932 KB Output is correct

Subtask #5
0.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 1 ms 860 KB Execution killed with signal 6
2 Halted 0 ms 0 KB -

Subtask #6
0.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 364 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 604 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 1 ms 344 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Runtime error 52 ms 30336 KB Execution killed with signal 6
12 Halted 0 ms 0 KB -