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Submission #640393

# Submission time Handle Problem Language Result Execution time Memory
640393 2022-09-14T14:16:07 Z chenwz Parking (CEOI22_parking) C++11
100 / 100
 471 ms 85360 KB 
#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pi;
const int MAXN = 400005;

int b[MAXN], t[MAXN], fa[MAXN], siz[MAXN], InCycle[MAXN], TPCnt[MAXN],
    cnt[MAXN];
set<int> Free, G[MAXN];
vector<int> Loc[MAXN];
vector<pair<pi, int> > red;
vector<pi> sol;
void move(int x, int y) {
  sol.push_back({x, y});
  if (++cnt[y] == 1) Free.erase(y);
  if (--cnt[x] == 0) Free.insert(x);
}
int find_set(int x) { return x == fa[x] ? x : fa[x] = find_set(fa[x]); }
void add_edge(int x, int y) {
  G[x].insert(y), G[y].insert(x);
  TPCnt[y] += (x % 2) && (y % 2);
  x = find_set(x), y = find_set(y);
  if (x == y)
    InCycle[x] = 1;
  else
    fa[x] = y, siz[y] += siz[x], TPCnt[y] += TPCnt[x];
}
void remove_edge(int x, int y) { G[x].erase(y), G[y].erase(x); }
int get_end_of_chain(int x, int last) {
  if (G[x].size() == 1) return x;
  assert(G[x].size() == 2);
  for (auto v : G[x])
    if (v != last) return get_end_of_chain(v, x);
  return -1;
}
bool solve_path(int idx) {
  int curr = get_end_of_chain(idx, -1), last = -1;
  vector<int> r;
  while (curr != -1) {
    r.push_back(curr);
    int nxt = -1;
    for (auto v : G[curr])
      if (v != last) nxt = v;
    last = curr, curr = nxt;
  }
  for (int i = 0, sz = r.size(); i < sz; i++) {
    if (r[i + 1] % 2 == 1) {
      move(r[i + 1] / 2, r[i] / 2), i++;
      continue;
    }
    int k = -1;
    for (int j = i; j < sz - 1; j++) {
      if (r[j] % 2 == 1 && r[j + 1] % 2 == 1) {
        k = j;
        break;
      }
    }
    if (k != -1) {
      if (Free.empty()) return false;
      int to = *Free.begin();
      move(r[k] / 2, to), move(r[k + 1] / 2, to);
      for (int j = k - 1; j >= i; j -= 2) move(r[j - 1] / 2, r[j] / 2);
      i = k + 1;
    } else {
      for (int j = sz - 1; j > i + 1; j -= 2) move(r[j - 1] / 2, r[j] / 2);
      move(r[i] / 2, r[i + 1] / 2);
      break;
    }
  }
  return true;
}

bool solve_cycle(int idx) {
  if (Free.empty()) return false;
  int pocetak = idx, curr = idx, last = -1;
  vector<int> r;
  while (curr != -1) {
    r.push_back(curr);
    int nxt = -1;
    for (auto v : G[curr]) {
      if (v == last || v == pocetak) continue;
      nxt = v;
    }
    last = curr, curr = nxt;
  }
  int R = r.size(), k = -1;
  for (int i = 0; i < R; i++) {
    if (r[i] % 2 == 1) k = i;
    if (r[i] % 2 == 1 && r[(i + 1) % R] % 2 == 1) {
      k = i;
      break;
    }
  }
  int x = r[k], y = r[(k + 1) % R];
  if (y % 2 == 1) {
    int to = *Free.begin();
    move(x / 2, to), move(y / 2, to);
    remove_edge(r[(k - 1 + R) % R], r[k]);
    remove_edge(r[k], r[(k + 1) % R]);
    remove_edge(r[(k + 1) % R], r[(k + 2) % R]);
    solve_path(r[(k + 2) % r.size()]);
  } else {
    int to = *Free.begin();
    if (x / 2 != y / 2) {
      move(x / 2, to);
      for (int i = 2; i < R; i += 2)
        move(r[(k - i + R) % R] / 2, r[(k - i + 1 + R) % R] / 2);
      move(y / 2, to);
    } else {
      move(x / 2, to);
      for (int i = 1; i + 1 < R; i += 2)
        move(r[(k + i + 1) % R] / 2, r[(k + i) % R] / 2);
      move(r[(k - 1 + R) % R] / 2, to);
    }
  }
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    cin >> b[i] >> t[i];
    if (b[i]) Loc[b[i]].push_back(2 * i);
    if (t[i]) Loc[t[i]].push_back(2 * i + 1);
    fa[2 * i] = 2 * i, siz[2 * i] = 1;
    fa[2 * i + 1] = 2 * i + 1, siz[2 * i + 1] = 1;
    cnt[i] = (b[i] > 0) + (t[i] > 0);
    if (cnt[i] == 0) Free.insert(i);
  }

  for (int i = 1; i <= n; i++) {
    int x = Loc[i][0], y = Loc[i][1];
    if (x / 2 != y / 2) add_edge(x, y);
  }
  for (int i = 0; i < m; i++)
    if (b[i] && t[i] && b[i] != t[i]) add_edge(2 * i, 2 * i + 1);
  for (int i = 0; i < 2 * m; i++)
    if (i == fa[i] && siz[i] > 1) red.push_back({{InCycle[i], TPCnt[i]}, i});
  sort(red.begin(), red.end());
  bool suc = true;
  for (auto p : red) {
    int idx = p.second;
    suc = !InCycle[idx] ? solve_path(idx) : solve_cycle(idx);
    if (!suc) break;
  }
  if (!suc) {
    cout << -1 << '\n';
  } else {
    cout << sol.size() << endl;
    for (auto p : sol) cout << p.first + 1 << " " << p.second + 1 << '\n';
  }
  return 0;
}

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 28500 KB Output is correct
2 Correct 15 ms 28500 KB Output is correct
3 Correct 14 ms 28500 KB Output is correct
4 Correct 15 ms 28500 KB Output is correct
5 Correct 15 ms 28472 KB Output is correct
6 Correct 14 ms 28500 KB Output is correct
7 Correct 15 ms 28500 KB Output is correct
8 Correct 14 ms 28500 KB Output is correct
9 Correct 15 ms 28428 KB Output is correct
10 Correct 16 ms 28500 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 194 ms 55816 KB Output is correct
2 Correct 246 ms 59320 KB Output is correct
3 Correct 155 ms 52204 KB Output is correct
4 Correct 142 ms 51540 KB Output is correct
5 Correct 237 ms 59152 KB Output is correct

Subtask #3
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 28628 KB Output is correct
2 Correct 15 ms 28500 KB Output is correct
3 Correct 16 ms 28768 KB Output is correct
4 Correct 16 ms 28820 KB Output is correct
5 Correct 16 ms 28724 KB Output is correct
6 Correct 17 ms 28884 KB Output is correct
7 Correct 17 ms 28756 KB Output is correct
8 Correct 14 ms 28748 KB Output is correct
9 Correct 21 ms 28816 KB Output is correct

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 20 ms 28628 KB Output is correct
2 Correct 15 ms 28500 KB Output is correct
3 Correct 16 ms 28768 KB Output is correct
4 Correct 16 ms 28820 KB Output is correct
5 Correct 16 ms 28724 KB Output is correct
6 Correct 17 ms 28884 KB Output is correct
7 Correct 17 ms 28756 KB Output is correct
8 Correct 14 ms 28748 KB Output is correct
9 Correct 21 ms 28816 KB Output is correct
10 Correct 471 ms 85360 KB Output is correct
11 Correct 83 ms 39864 KB Output is correct
12 Correct 324 ms 78212 KB Output is correct
13 Correct 439 ms 82696 KB Output is correct
14 Correct 316 ms 80320 KB Output is correct
15 Correct 318 ms 78344 KB Output is correct
16 Correct 462 ms 85296 KB Output is correct
17 Correct 365 ms 78768 KB Output is correct
18 Correct 464 ms 84480 KB Output is correct

Subtask #5
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 28756 KB Output is correct
2 Correct 17 ms 28756 KB Output is correct
3 Correct 16 ms 28680 KB Output is correct
4 Correct 18 ms 28628 KB Output is correct
5 Correct 18 ms 28540 KB Output is correct
6 Correct 17 ms 28740 KB Output is correct
7 Correct 20 ms 28756 KB Output is correct
8 Correct 18 ms 28796 KB Output is correct
9 Correct 15 ms 28740 KB Output is correct
10 Correct 15 ms 28756 KB Output is correct
11 Correct 15 ms 28756 KB Output is correct
12 Correct 16 ms 28756 KB Output is correct
13 Correct 15 ms 28756 KB Output is correct
14 Correct 17 ms 28772 KB Output is correct
15 Correct 14 ms 28756 KB Output is correct
16 Correct 16 ms 28880 KB Output is correct
17 Correct 16 ms 28804 KB Output is correct
18 Correct 16 ms 28728 KB Output is correct
19 Correct 17 ms 28756 KB Output is correct
20 Correct 16 ms 28740 KB Output is correct
21 Correct 16 ms 28756 KB Output is correct
22 Correct 16 ms 28756 KB Output is correct
23 Correct 18 ms 28756 KB Output is correct
24 Correct 18 ms 28756 KB Output is correct

Subtask #6
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 28500 KB Output is correct
2 Correct 15 ms 28500 KB Output is correct
3 Correct 14 ms 28500 KB Output is correct
4 Correct 15 ms 28500 KB Output is correct
5 Correct 15 ms 28472 KB Output is correct
6 Correct 14 ms 28500 KB Output is correct
7 Correct 15 ms 28500 KB Output is correct
8 Correct 14 ms 28500 KB Output is correct
9 Correct 15 ms 28428 KB Output is correct
10 Correct 16 ms 28500 KB Output is correct
11 Correct 194 ms 55816 KB Output is correct
12 Correct 246 ms 59320 KB Output is correct
13 Correct 155 ms 52204 KB Output is correct
14 Correct 142 ms 51540 KB Output is correct
15 Correct 237 ms 59152 KB Output is correct
16 Correct 20 ms 28628 KB Output is correct
17 Correct 15 ms 28500 KB Output is correct
18 Correct 16 ms 28768 KB Output is correct
19 Correct 16 ms 28820 KB Output is correct
20 Correct 16 ms 28724 KB Output is correct
21 Correct 17 ms 28884 KB Output is correct
22 Correct 17 ms 28756 KB Output is correct
23 Correct 14 ms 28748 KB Output is correct
24 Correct 21 ms 28816 KB Output is correct
25 Correct 471 ms 85360 KB Output is correct
26 Correct 83 ms 39864 KB Output is correct
27 Correct 324 ms 78212 KB Output is correct
28 Correct 439 ms 82696 KB Output is correct
29 Correct 316 ms 80320 KB Output is correct
30 Correct 318 ms 78344 KB Output is correct
31 Correct 462 ms 85296 KB Output is correct
32 Correct 365 ms 78768 KB Output is correct
33 Correct 464 ms 84480 KB Output is correct
34 Correct 15 ms 28756 KB Output is correct
35 Correct 17 ms 28756 KB Output is correct
36 Correct 16 ms 28680 KB Output is correct
37 Correct 18 ms 28628 KB Output is correct
38 Correct 18 ms 28540 KB Output is correct
39 Correct 17 ms 28740 KB Output is correct
40 Correct 20 ms 28756 KB Output is correct
41 Correct 18 ms 28796 KB Output is correct
42 Correct 15 ms 28740 KB Output is correct
43 Correct 15 ms 28756 KB Output is correct
44 Correct 15 ms 28756 KB Output is correct
45 Correct 16 ms 28756 KB Output is correct
46 Correct 15 ms 28756 KB Output is correct
47 Correct 17 ms 28772 KB Output is correct
48 Correct 14 ms 28756 KB Output is correct
49 Correct 16 ms 28880 KB Output is correct
50 Correct 16 ms 28804 KB Output is correct
51 Correct 16 ms 28728 KB Output is correct
52 Correct 17 ms 28756 KB Output is correct
53 Correct 16 ms 28740 KB Output is correct
54 Correct 16 ms 28756 KB Output is correct
55 Correct 16 ms 28756 KB Output is correct
56 Correct 18 ms 28756 KB Output is correct
57 Correct 18 ms 28756 KB Output is correct
58 Correct 392 ms 77664 KB Output is correct
59 Correct 436 ms 82956 KB Output is correct
60 Correct 359 ms 72332 KB Output is correct
61 Correct 404 ms 80548 KB Output is correct
62 Correct 80 ms 40140 KB Output is correct
63 Correct 404 ms 81256 KB Output is correct
64 Correct 325 ms 78956 KB Output is correct
65 Correct 423 ms 81756 KB Output is correct
66 Correct 435 ms 84060 KB Output is correct
67 Correct 289 ms 77108 KB Output is correct
68 Correct 422 ms 83360 KB Output is correct
69 Correct 414 ms 81672 KB Output is correct
70 Correct 284 ms 77196 KB Output is correct
71 Correct 310 ms 79692 KB Output is correct
72 Correct 304 ms 78912 KB Output is correct
73 Correct 439 ms 85148 KB Output is correct
74 Correct 296 ms 78428 KB Output is correct
75 Correct 430 ms 83784 KB Output is correct
76 Correct 461 ms 84700 KB Output is correct
77 Correct 423 ms 83068 KB Output is correct
78 Correct 306 ms 78908 KB Output is correct
79 Correct 465 ms 82588 KB Output is correct
80 Correct 350 ms 79220 KB Output is correct
81 Correct 431 ms 83564 KB Output is correct