oj.uz

답안 #627257

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
627257 2022-08-12T11:44:37 Z model_code 수천개의 섬 (IOI22_islands) C++17
100 / 100
 360 ms 47916 KB 
// model_solution/solution.cpp
#include "islands.h"

#include <bits/stdc++.h>

#define edge std::pair<int,int>


int mode[111000];

std::vector<std::set<edge>> back_path(222000);
std::vector<std::set<edge>> path(222000);
std::queue<int> remove_q;

bool must_flip = false;

int path_1_loop, path_2_loop;


void put_path(std::vector<int> &sol, std::vector<int> &mirror_sol, std::vector<std::pair<int, int>> &path_1, int loop_id) {
  bool start = false;
  for (int i = 1; i < (int) path_1.size(); i++) {
      int u = path_1[i - 1].first;
      int v = path_1[i].first;

      if ((!start && u == loop_id) || (start && v == loop_id)) {
        start = 1;
        mirror_sol.push_back(1);
      }
      else
        mirror_sol.push_back(0);

      if (path_1[i].second == 1)
        sol.push_back(path[u].begin()->first);
      else
        sol.push_back(path[v].begin()->first);  
    }
}

// remove a node X
void remove_node(int X) {
  // remove node 'curr', and all paths from/to them
    for (auto e: back_path[X]) {
      auto e_id = e.first;
      auto v = e.second;
      path[v].erase({e_id, X});
      if ((int) path[v].size() == 0) remove_q.push(v);
    }

    for (auto e: path[X]) {
      auto e_id = e.first;
      auto v = e.second;
      back_path[v].erase({e_id, X});
    } 
}

// chain-remove all 0 outdegrees
void clear_unused_nodes() {
  while (remove_q.size()) {
    int curr = remove_q.front();
    remove_q.pop();

    remove_node(curr);  
  }
}

std::variant<bool, std::vector<int>> find_journey(int N, int M, std::vector<int> U, std::vector<int> V) {
  // construct the graph
  for (int i = 0; i < M; i++) {
    path[U[i]].insert({i, V[i]});
    back_path[V[i]].insert({i, U[i]});
  }

  for (int i = 0; i < N; i++)
    if ((int) path[i].size() == 0) remove_q.push(i);
  
  int START = 0;
  std::vector<int> backtrack;
  std::vector<int> init_sol;
  std::vector<int> back_sol;

  while (true) {
    clear_unused_nodes();
    // if START is removed, then no solution
    if ((int) path[START].size() == 0) return false;

    // if START outdeg is 1, move forward and start from there.



    if ((int) path[START].size() == 1) {
      backtrack.push_back(START);
      auto prev_start = START;
      init_sol.push_back(path[START].begin()->first);
      back_sol.push_back(path[START].begin()->first);

      START = path[START].begin()->second;
      
      remove_node(prev_start);
      continue;
    }

 
    // now, we start at START, which has >= 2 outdeg.
    // find a solution.

    // step 1: find a loop
    bool seen[111000];
    memset(seen, 0, sizeof(seen));

    // path notation: second denotes direction
    std::vector<std::pair<int, int>> path_1;
    std::vector<int> first_loop;


    int curr = START;

    while (true) {
      path_1.push_back({curr, 1});
      mode[curr] = 1;
      // loop found
      if (seen[curr]) {
        path_1_loop = curr;
        int X = path_1.size();
        
        bool reverse_mode = false;
        for (int i = X - 1; i >= 0; i--) {
          if (reverse_mode) {
            path_1.push_back({path_1[i].first, 0});
          }
          else {
            // the loop
            first_loop.push_back(path_1[i].first);
            mode[path_1[i].first] = 2;
          }
          if (i != X - 1 && path_1[i].first == curr) reverse_mode = true;
        }

        break;
      } 

      seen[curr] = 1;
      int next = path[curr].begin()->second;  /// guaranteed exists
      curr = next;
    }

    // step 2: find another loop
    // path notation: second denotes direction
    std::vector<std::pair<int, int>> path_2;

    curr = path[START].rbegin()->second;

    while (true) {

      path_2_loop = curr;
      path_2.push_back({curr, 1});
      if (seen[curr]) {
        // 3 cases:
        // 1st cases, found a straight path from path_1.
        if (mode[curr] == 1) {
          int curr2 = path[curr].begin()->second;

          while (mode[curr2] == 1) {
            path_2.push_back({curr2, 1});
            curr2 = path[curr2].begin()->second;
          }
          //backloop
          path_2.push_back({first_loop[0], 1});
          for (int i = 1; i < (int) first_loop.size(); i++) {
            path_2.push_back({first_loop[i], 0});
          }
          // set for trackback
          curr = first_loop[0];
        }

        else if (mode[curr] == 2) {
          // go back reverse circle
          // find the starting point
          int st = 0;
          for (int i = 0; i < (int) first_loop.size(); i++) {
            if (first_loop[i] == curr) {
              st = i + 1;
              break;
            }
          }

          // from st to end
          for (int i = st; i < (int) first_loop.size(); i++) {
            path_2.push_back({first_loop[i], 0});
          }
          // from begin to st
          for (int i = 1; i < st; i++) {
              path_2.push_back({first_loop[i], 0});
          }
        } else if (mode[curr] == 3) {
          must_flip = true;
        }

        int X = path_2.size();
        
        bool reverse_mode = false;
        for (int i = X - 1; i >= 0; i--) {
          if (reverse_mode) {
            path_2.push_back({path_2[i].first, 0});
          }
          if (i != X - 1 && path_2[i].first == curr) reverse_mode = true;
        }
        break;
      }
      mode[curr] = 3;
      seen[curr] = 1;
      curr = path[curr].begin()->second;
    }

    // has a solution
    // convert paths to edges
    std::vector<int> sol;
    std::vector<int> mirror_sol;


    put_path(sol, mirror_sol, path_1, path_1_loop);
    mirror_sol.push_back(0);
    sol.push_back(path[START].rbegin()->first);

    put_path(sol, mirror_sol, path_2, path_2_loop);
    
    mirror_sol.push_back(0);
    sol.push_back(path[START].rbegin()->first);

    
    if (must_flip) {
      int X = sol.size();
      std::stack<int> stack_path;
      bool stack_fill_mode = 0;

      for (int i = 0; i < X; i++) {
        while (!stack_fill_mode && stack_path.size()) {
          int tmp = stack_path.top();
          stack_path.pop();
          sol.push_back(tmp);
        }
        if (mirror_sol[i] == 1) {
          stack_fill_mode ^= 1;
        }

        if (stack_fill_mode)
          stack_path.push(sol[i]);
        else
          sol.push_back(sol[i]);
      }
    }


    for (auto x: sol){
      init_sol.push_back(x);
    }

    std::reverse(back_sol.begin(), back_sol.end());
    for (auto x: back_sol){
      init_sol.push_back(x);
    }

    return init_sol;
  }
}

Subtask #1
5.0 / 5.0

# 결과 실행 시간 메모리 Grader output
1 Correct 11 ms 21204 KB Output is correct
2 Correct 11 ms 21204 KB Output is correct
3 Correct 11 ms 21204 KB Output is correct
4 Correct 11 ms 21204 KB Output is correct
5 Correct 12 ms 21204 KB Output is correct
6 Correct 11 ms 21248 KB Output is correct
7 Correct 120 ms 43076 KB Output is correct

Subtask #2
5.0 / 5.0

# 결과 실행 시간 메모리 Grader output
1 Correct 11 ms 21204 KB Output is correct
2 Correct 11 ms 21204 KB Output is correct
3 Correct 11 ms 21204 KB Output is correct
4 Correct 12 ms 21160 KB Output is correct
5 Correct 11 ms 21204 KB Output is correct
6 Correct 138 ms 38696 KB Output is correct

Subtask #3
21.0 / 21.0

# 결과 실행 시간 메모리 Grader output
1 Correct 16 ms 21716 KB Output is correct
2 Correct 11 ms 21204 KB Output is correct
3 Correct 11 ms 21204 KB Output is correct
4 Correct 11 ms 21204 KB Output is correct
5 Correct 12 ms 21496 KB Output is correct
6 Correct 11 ms 21204 KB Output is correct
7 Correct 13 ms 21332 KB Output is correct
8 Correct 11 ms 21204 KB Output is correct
9 Correct 12 ms 21220 KB Output is correct
10 Correct 12 ms 21460 KB Output is correct
11 Correct 12 ms 21184 KB Output is correct
12 Correct 14 ms 21460 KB Output is correct
13 Correct 11 ms 21280 KB Output is correct
14 Correct 11 ms 21256 KB Output is correct
15 Correct 11 ms 21312 KB Output is correct
16 Correct 11 ms 21204 KB Output is correct
17 Correct 82 ms 32216 KB Output is correct
18 Correct 58 ms 29996 KB Output is correct
19 Correct 11 ms 21204 KB Output is correct
20 Correct 12 ms 21204 KB Output is correct
21 Correct 14 ms 21184 KB Output is correct
22 Correct 11 ms 21204 KB Output is correct
23 Correct 134 ms 38716 KB Output is correct

Subtask #4
24.0 / 24.0

# 결과 실행 시간 메모리 Grader output
1 Correct 11 ms 21204 KB Output is correct
2 Correct 13 ms 21716 KB Output is correct
3 Correct 175 ms 40996 KB Output is correct
4 Correct 184 ms 40868 KB Output is correct
5 Correct 13 ms 21588 KB Output is correct
6 Correct 14 ms 21716 KB Output is correct
7 Correct 11 ms 21244 KB Output is correct
8 Correct 11 ms 21204 KB Output is correct
9 Correct 11 ms 21204 KB Output is correct
10 Correct 13 ms 21568 KB Output is correct
11 Correct 13 ms 21588 KB Output is correct
12 Correct 13 ms 21716 KB Output is correct
13 Correct 13 ms 21676 KB Output is correct
14 Correct 13 ms 21716 KB Output is correct
15 Correct 14 ms 21844 KB Output is correct
16 Correct 12 ms 21460 KB Output is correct
17 Correct 11 ms 21204 KB Output is correct
18 Correct 13 ms 21716 KB Output is correct
19 Correct 14 ms 21440 KB Output is correct
20 Correct 192 ms 43256 KB Output is correct
21 Correct 183 ms 40880 KB Output is correct
22 Correct 12 ms 21496 KB Output is correct
23 Correct 11 ms 21384 KB Output is correct
24 Correct 11 ms 21204 KB Output is correct
25 Correct 12 ms 21460 KB Output is correct
26 Correct 14 ms 21588 KB Output is correct
27 Correct 179 ms 42084 KB Output is correct
28 Correct 185 ms 42040 KB Output is correct
29 Correct 11 ms 21204 KB Output is correct
30 Correct 203 ms 43076 KB Output is correct
31 Correct 15 ms 21204 KB Output is correct
32 Correct 194 ms 40872 KB Output is correct
33 Correct 180 ms 42084 KB Output is correct
34 Correct 66 ms 32220 KB Output is correct
35 Correct 11 ms 21344 KB Output is correct
36 Correct 160 ms 38800 KB Output is correct
37 Correct 162 ms 42028 KB Output is correct
38 Correct 11 ms 21460 KB Output is correct
39 Correct 156 ms 38132 KB Output is correct
40 Correct 11 ms 21448 KB Output is correct
41 Correct 196 ms 43128 KB Output is correct
42 Correct 179 ms 41996 KB Output is correct
43 Correct 11 ms 21204 KB Output is correct
44 Correct 12 ms 21696 KB Output is correct
45 Correct 11 ms 21588 KB Output is correct
46 Correct 51 ms 30024 KB Output is correct

Subtask #5
45.0 / 45.0

# 결과 실행 시간 메모리 Grader output
1 Correct 11 ms 21204 KB Output is correct
2 Correct 11 ms 21204 KB Output is correct
3 Correct 11 ms 21204 KB Output is correct
4 Correct 11 ms 21204 KB Output is correct
5 Correct 12 ms 21204 KB Output is correct
6 Correct 11 ms 21248 KB Output is correct
7 Correct 120 ms 43076 KB Output is correct
8 Correct 11 ms 21204 KB Output is correct
9 Correct 11 ms 21204 KB Output is correct
10 Correct 11 ms 21204 KB Output is correct
11 Correct 12 ms 21160 KB Output is correct
12 Correct 11 ms 21204 KB Output is correct
13 Correct 138 ms 38696 KB Output is correct
14 Correct 16 ms 21716 KB Output is correct
15 Correct 11 ms 21204 KB Output is correct
16 Correct 11 ms 21204 KB Output is correct
17 Correct 11 ms 21204 KB Output is correct
18 Correct 12 ms 21496 KB Output is correct
19 Correct 11 ms 21204 KB Output is correct
20 Correct 13 ms 21332 KB Output is correct
21 Correct 11 ms 21204 KB Output is correct
22 Correct 12 ms 21220 KB Output is correct
23 Correct 12 ms 21460 KB Output is correct
24 Correct 12 ms 21184 KB Output is correct
25 Correct 14 ms 21460 KB Output is correct
26 Correct 11 ms 21280 KB Output is correct
27 Correct 11 ms 21256 KB Output is correct
28 Correct 11 ms 21312 KB Output is correct
29 Correct 11 ms 21204 KB Output is correct
30 Correct 82 ms 32216 KB Output is correct
31 Correct 58 ms 29996 KB Output is correct
32 Correct 11 ms 21204 KB Output is correct
33 Correct 12 ms 21204 KB Output is correct
34 Correct 14 ms 21184 KB Output is correct
35 Correct 11 ms 21204 KB Output is correct
36 Correct 134 ms 38716 KB Output is correct
37 Correct 10 ms 21280 KB Output is correct
38 Correct 10 ms 21204 KB Output is correct
39 Correct 15 ms 21300 KB Output is correct
40 Correct 11 ms 21284 KB Output is correct
41 Correct 89 ms 31120 KB Output is correct
42 Correct 13 ms 21828 KB Output is correct
43 Correct 134 ms 32184 KB Output is correct
44 Correct 103 ms 32172 KB Output is correct
45 Correct 100 ms 32236 KB Output is correct
46 Correct 10 ms 21184 KB Output is correct
47 Correct 10 ms 21248 KB Output is correct
48 Correct 10 ms 21272 KB Output is correct
49 Correct 14 ms 21480 KB Output is correct
50 Correct 142 ms 38712 KB Output is correct
51 Correct 220 ms 43084 KB Output is correct
52 Correct 226 ms 43148 KB Output is correct
53 Correct 257 ms 43444 KB Output is correct
54 Correct 254 ms 43196 KB Output is correct
55 Correct 253 ms 43172 KB Output is correct
56 Correct 280 ms 43188 KB Output is correct
57 Correct 147 ms 42588 KB Output is correct
58 Correct 178 ms 39172 KB Output is correct
59 Correct 286 ms 43324 KB Output is correct
60 Correct 321 ms 43332 KB Output is correct
61 Correct 265 ms 43300 KB Output is correct
62 Correct 41 ms 24880 KB Output is correct
63 Correct 196 ms 42160 KB Output is correct
64 Correct 180 ms 32168 KB Output is correct
65 Correct 15 ms 21196 KB Output is correct
66 Correct 20 ms 21332 KB Output is correct
67 Correct 210 ms 43664 KB Output is correct
68 Correct 334 ms 43192 KB Output is correct
69 Correct 130 ms 32308 KB Output is correct
70 Correct 14 ms 21460 KB Output is correct
71 Correct 219 ms 37716 KB Output is correct
72 Correct 15 ms 21272 KB Output is correct
73 Correct 333 ms 43164 KB Output is correct
74 Correct 179 ms 38536 KB Output is correct
75 Correct 26 ms 22308 KB Output is correct
76 Correct 90 ms 29076 KB Output is correct
77 Correct 133 ms 32296 KB Output is correct
78 Correct 341 ms 43376 KB Output is correct
79 Correct 14 ms 21204 KB Output is correct
80 Correct 360 ms 47916 KB Output is correct
81 Correct 14 ms 21468 KB Output is correct
82 Correct 237 ms 43068 KB Output is correct
83 Correct 12 ms 21332 KB Output is correct
84 Correct 13 ms 21272 KB Output is correct
85 Correct 72 ms 28728 KB Output is correct
86 Correct 12 ms 21460 KB Output is correct
87 Correct 12 ms 21716 KB Output is correct
88 Correct 16 ms 21844 KB Output is correct
89 Correct 316 ms 43340 KB Output is correct
90 Correct 287 ms 43304 KB Output is correct
91 Correct 320 ms 46296 KB Output is correct
92 Correct 14 ms 21204 KB Output is correct