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Submission #627258

# Submission time Handle Problem Language Result Execution time Memory
627258 2022-08-12T11:44:51 Z model_code Thousands Islands (IOI22_islands) C++17
100 / 100
 425 ms 44136 KB 
// correct/solution-ayaze-full.cpp
#include "islands.h"

#include <bits/stdc++.h>
using namespace std;

vector<set<pair<int, int>>> adj_list, rev_adj_list;
queue<int> unprocessed_zero_outdeg;

void RemoveNode(int v) {
  for (auto [u, edge_idx] : adj_list[v]) {
    rev_adj_list[u].erase({v, edge_idx});
  }

  for (auto [u, edge_idx] : rev_adj_list[v]) {
    adj_list[u].erase({v, edge_idx});

    if (adj_list[u].empty()) {
      unprocessed_zero_outdeg.push(u);
    }
  }

  adj_list[v].clear();
  rev_adj_list[v].clear();
}

// nodes, edge idxs
// last node is the first cyclic node
pair<vector<int>, vector<int>> FindCycle(int u, bool take_second) {
  auto it = adj_list[u].begin();
  if (take_second) ++it;

  set<int> seen = {u};
  vector<int> nodes = {u};
  vector<int> edge_idxs = {};

  auto [v, edge_idx] = *it;
  while (!seen.count(v)) {
    nodes.push_back(v);
    edge_idxs.push_back(edge_idx);
    seen.insert(v);

    edge_idx = adj_list[v].begin()->second;
    v = adj_list[v].begin()->first;
  }

  nodes.push_back(v);
  edge_idxs.push_back(edge_idx);
  return {nodes, edge_idxs};
}

pair<vector<int>, vector<int>> ConstructSimpleCycle(vector<int> nodes, vector<int> edge_idxs) {
  int first_occ = -1;
  for (int i = 0 ; i+1 < static_cast<int>(nodes.size()) ; i++) {
    if (nodes[i] == nodes.back()) {
      first_occ = i;
      break;
    }
  }

  vector<int> first_path;
  for (int i = 0 ; i < static_cast<int>(edge_idxs.size()) ; i++) {
    first_path.push_back(edge_idxs[i]);
  }
  for (int i = first_occ-1 ; i >= 0 ; i--) {
    first_path.push_back(edge_idxs[i]);
  }

  vector<int> second_path;
  for (int i = 0 ; i < first_occ ; i++) {
    second_path.push_back(edge_idxs[i]);
  }
  for (int i = static_cast<int>(edge_idxs.size())-1 ; i >= 0 ; i--) {
    second_path.push_back(edge_idxs[i]);
  }

  return {first_path, second_path};
}

void FindTour(int u, vector<int> &ans) {
  while (!unprocessed_zero_outdeg.empty()) {
    int v = unprocessed_zero_outdeg.front();
    unprocessed_zero_outdeg.pop();
    RemoveNode(v);
  }

  if (adj_list[u].empty()) {
    ans.push_back(-1);
    return;
  }

  if (static_cast<int>(adj_list[u].size()) == 1) {
    auto [v, edge_idx] = *adj_list[u].begin();
    ans.push_back(edge_idx);
    RemoveNode(u);
    FindTour(v, ans);
    ans.push_back(edge_idx);
    return;
  }

  auto [first_cycle, first_cycle_edges] = FindCycle(u, false);
  auto [second_cycle, second_cycle_edges] = FindCycle(u, true);

  map<int, int> first_occ;
  for (int i = 0 ; i+1 < static_cast<int>(first_cycle.size()) ; i++) {
    first_occ[first_cycle[i]] = i;
  }
  int common_node = -1;
  int first_common_occ = -1;
  int second_common_occ = -1;
  for (int i = 1 ; i+1 < static_cast<int>(second_cycle.size()) ; i++) {
    if (first_occ.count(second_cycle[i])) {
      common_node = second_cycle[i];
      second_common_occ = i;
      first_common_occ = first_occ[common_node];
      break;
    }
  }

  if (common_node == -1) { // two disjoint cycles
    auto cycle1 = ConstructSimpleCycle(first_cycle, first_cycle_edges);
    auto cycle2 = ConstructSimpleCycle(second_cycle, second_cycle_edges);

    ans.insert(ans.end(), cycle1.first.begin(), cycle1.first.end());
    ans.insert(ans.end(), cycle2.first.begin(), cycle2.first.end());
    ans.insert(ans.end(), cycle1.second.begin(), cycle1.second.end());
    ans.insert(ans.end(), cycle2.second.begin(), cycle2.second.end());
    return;
  }

  int first_cyclic_occ = -1;
  for (int i = 0 ; i+1 < static_cast<int>(first_cycle.size()) ; i++) {
    if (first_cycle[i] == first_cycle.back()) {
      first_cyclic_occ = i;
      break;
    }
  }
  
  // loop the first path
  for (int i = 0 ; i < static_cast<int>(first_cycle_edges.size()) ; i++) {
    ans.push_back(first_cycle_edges[i]);
  }
  for (int i = first_cyclic_occ-1 ; i >= 0 ; i--) {
    ans.push_back(first_cycle_edges[i]);
  }

  // enter first path through second path
  for (int i = 0 ; i < second_common_occ ; i++) {
    ans.push_back(second_cycle_edges[i]);
  }

  // only one of the following loops will be executed; we want
  // to reach the start of the cycle
  for (int i = first_common_occ-1 ; i >= first_cyclic_occ ; i--) {
    ans.push_back(first_cycle_edges[i]);
  }
  for (int i = first_common_occ ; i < first_cyclic_occ ; i++) {
    ans.push_back(first_cycle_edges[i]);
  }

  // go back through the latter part of first path and second path
  for (int i = static_cast<int>(first_cycle_edges.size())-1 ; i >= first_common_occ ; i--) {
    ans.push_back(first_cycle_edges[i]);
  }
  for (int i = second_common_occ-1 ; i >= 0 ; i--) {
    ans.push_back(second_cycle_edges[i]);
  }
}

std::variant<bool, std::vector<int>> find_journey(
    int N, int M, std::vector<int> U, std::vector<int> V) {
  
  adj_list.resize(N);
  rev_adj_list.resize(N);
  for (int i = 0 ; i < M ; i++) {
    adj_list[U[i]].insert({V[i], i});
    rev_adj_list[V[i]].insert({U[i], i});
  }
  for (int i = 0 ; i < N ; i++) {
    if (adj_list[i].empty()) {
      unprocessed_zero_outdeg.push(i);
    }
  }

  vector<int> ret;
  FindTour(0, ret);

  for (int e : ret) {
    if (e == -1) {
      return false;
    }
  }

  return ret;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 124 ms 22116 KB Output is correct

Subtask #2
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 151 ms 17796 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 724 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 3 ms 980 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 2 ms 724 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 2 ms 852 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 1 ms 212 KB Output is correct
15 Correct 0 ms 212 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 136 ms 11324 KB Output is correct
18 Correct 77 ms 9104 KB Output is correct
19 Correct 1 ms 212 KB Output is correct
20 Correct 1 ms 212 KB Output is correct
21 Correct 1 ms 212 KB Output is correct
22 Correct 0 ms 212 KB Output is correct
23 Correct 159 ms 17740 KB Output is correct

Subtask #4
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 3 ms 724 KB Output is correct
3 Correct 223 ms 20028 KB Output is correct
4 Correct 228 ms 20124 KB Output is correct
5 Correct 3 ms 784 KB Output is correct
6 Correct 3 ms 724 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 3 ms 596 KB Output is correct
11 Correct 4 ms 712 KB Output is correct
12 Correct 4 ms 724 KB Output is correct
13 Correct 4 ms 852 KB Output is correct
14 Correct 2 ms 852 KB Output is correct
15 Correct 9 ms 980 KB Output is correct
16 Correct 2 ms 596 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 2 ms 724 KB Output is correct
19 Correct 2 ms 596 KB Output is correct
20 Correct 274 ms 22192 KB Output is correct
21 Correct 230 ms 20012 KB Output is correct
22 Correct 1 ms 596 KB Output is correct
23 Correct 1 ms 468 KB Output is correct
24 Correct 1 ms 212 KB Output is correct
25 Correct 2 ms 468 KB Output is correct
26 Correct 2 ms 596 KB Output is correct
27 Correct 262 ms 21124 KB Output is correct
28 Correct 285 ms 21160 KB Output is correct
29 Correct 1 ms 256 KB Output is correct
30 Correct 298 ms 22300 KB Output is correct
31 Correct 1 ms 212 KB Output is correct
32 Correct 224 ms 20004 KB Output is correct
33 Correct 241 ms 21132 KB Output is correct
34 Correct 87 ms 11332 KB Output is correct
35 Correct 1 ms 468 KB Output is correct
36 Correct 203 ms 17932 KB Output is correct
37 Correct 217 ms 21104 KB Output is correct
38 Correct 1 ms 468 KB Output is correct
39 Correct 181 ms 17224 KB Output is correct
40 Correct 2 ms 592 KB Output is correct
41 Correct 212 ms 22204 KB Output is correct
42 Correct 297 ms 21112 KB Output is correct
43 Correct 1 ms 212 KB Output is correct
44 Correct 3 ms 724 KB Output is correct
45 Correct 4 ms 596 KB Output is correct
46 Correct 81 ms 9060 KB Output is correct

Subtask #5
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 124 ms 22116 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 0 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 0 ms 212 KB Output is correct
13 Correct 151 ms 17796 KB Output is correct
14 Correct 4 ms 724 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 0 ms 212 KB Output is correct
17 Correct 0 ms 212 KB Output is correct
18 Correct 3 ms 980 KB Output is correct
19 Correct 0 ms 212 KB Output is correct
20 Correct 1 ms 468 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 1 ms 212 KB Output is correct
23 Correct 2 ms 724 KB Output is correct
24 Correct 0 ms 212 KB Output is correct
25 Correct 2 ms 852 KB Output is correct
26 Correct 0 ms 212 KB Output is correct
27 Correct 1 ms 212 KB Output is correct
28 Correct 0 ms 212 KB Output is correct
29 Correct 1 ms 340 KB Output is correct
30 Correct 136 ms 11324 KB Output is correct
31 Correct 77 ms 9104 KB Output is correct
32 Correct 1 ms 212 KB Output is correct
33 Correct 1 ms 212 KB Output is correct
34 Correct 1 ms 212 KB Output is correct
35 Correct 0 ms 212 KB Output is correct
36 Correct 159 ms 17740 KB Output is correct
37 Correct 0 ms 212 KB Output is correct
38 Correct 1 ms 212 KB Output is correct
39 Correct 1 ms 212 KB Output is correct
40 Correct 1 ms 340 KB Output is correct
41 Correct 111 ms 10096 KB Output is correct
42 Correct 4 ms 852 KB Output is correct
43 Correct 135 ms 15996 KB Output is correct
44 Correct 117 ms 15992 KB Output is correct
45 Correct 148 ms 16076 KB Output is correct
46 Correct 1 ms 212 KB Output is correct
47 Correct 1 ms 212 KB Output is correct
48 Correct 1 ms 212 KB Output is correct
49 Correct 5 ms 724 KB Output is correct
50 Correct 288 ms 44136 KB Output is correct
51 Correct 367 ms 31668 KB Output is correct
52 Correct 322 ms 31660 KB Output is correct
53 Correct 331 ms 31652 KB Output is correct
54 Correct 365 ms 31616 KB Output is correct
55 Correct 332 ms 31616 KB Output is correct
56 Correct 358 ms 31504 KB Output is correct
57 Correct 276 ms 27732 KB Output is correct
58 Correct 240 ms 26300 KB Output is correct
59 Correct 327 ms 31736 KB Output is correct
60 Correct 345 ms 31840 KB Output is correct
61 Correct 270 ms 31720 KB Output is correct
62 Correct 33 ms 8076 KB Output is correct
63 Correct 205 ms 30380 KB Output is correct
64 Correct 142 ms 11416 KB Output is correct
65 Correct 0 ms 212 KB Output is correct
66 Correct 1 ms 340 KB Output is correct
67 Correct 216 ms 31664 KB Output is correct
68 Correct 394 ms 22312 KB Output is correct
69 Correct 143 ms 20804 KB Output is correct
70 Correct 2 ms 596 KB Output is correct
71 Correct 214 ms 21468 KB Output is correct
72 Correct 0 ms 212 KB Output is correct
73 Correct 336 ms 28812 KB Output is correct
74 Correct 244 ms 28744 KB Output is correct
75 Correct 8 ms 1492 KB Output is correct
76 Correct 90 ms 12528 KB Output is correct
77 Correct 113 ms 21960 KB Output is correct
78 Correct 353 ms 31808 KB Output is correct
79 Correct 1 ms 212 KB Output is correct
80 Correct 392 ms 33748 KB Output is correct
81 Correct 4 ms 468 KB Output is correct
82 Correct 235 ms 22220 KB Output is correct
83 Correct 1 ms 468 KB Output is correct
84 Correct 1 ms 212 KB Output is correct
85 Correct 89 ms 13044 KB Output is correct
86 Correct 2 ms 596 KB Output is correct
87 Correct 7 ms 8148 KB Output is correct
88 Correct 4 ms 980 KB Output is correct
89 Correct 336 ms 32016 KB Output is correct
90 Correct 278 ms 31728 KB Output is correct
91 Correct 425 ms 33604 KB Output is correct
92 Correct 0 ms 212 KB Output is correct