oj.uz

Submission #499604

# Submission time Handle Problem Language Result Execution time Memory
499604 2021-12-29T01:43:18 Z CatalinT Simurgh (IOI17_simurgh) C++17
100 / 100
 566 ms 7880 KB 
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <set>
#include <vector>
#include <numeric>
#include <algorithm>
#include <iostream>
#include <string>
#include <cstring>
#include <sstream>
#include <functional>
#include <queue>
#include <deque>
#include <stack>
#include <cassert>
#include <iomanip>
#include <cmath>
#include <bitset>
 
using namespace std;

#include "simurgh.h"

using int64 = long long;

int N, M, Q;
vector<vector<int>> eidx;
vector<vector<int>> adj;
vector<int> par;
vector<int> depth;
vector<char> used;

vector<int> status;

vector<int> tree_idx;
vector<int> back_idx;
vector<int> all_idx;

vector<char> is_tree;
vector<char> added;

int get(int u, int v) {
    assert(eidx[u][v] != -1);
    return eidx[u][v];
}

void dfs(int n, int p) {
    //cerr << n << " " << p << "\n";
    used[n] = true;
    for (auto v : adj[n]) {
        if (v != p) {
            int e = get(n, v);
           
            if (!used[v]) {
                // Forward edge
                par[v] = n;
                depth[v] = depth[n] + 1;
                tree_idx.push_back(e);
                all_idx.push_back(e);
                is_tree[e] = 1;
                dfs(v, n);
            } else if (!added[e]) {
                added[e] = true;
                back_idx.push_back(e);
                all_idx.push_back(e);
            }
        }
    }
}

void redo_par(int n, int p) {
    for (auto v : adj[n]) {
        if (v != p) {
            int e = get(n, v);
            if (!is_tree[e])
                continue;
            par[v] = n;
            redo_par(v, n);
        }
    }
}

vector<int> get_cycle(int u, int v) {
    vector<int> edges;
    
    auto go_up = [&] (int & el) {
        edges.push_back(get(el, par[el]));
        el = par[el];
    };

    while(depth[u] > depth[v]) {
        go_up(u);
    }
    while(depth[u] < depth[v]) {
        go_up(v);
    }
    while(u != v) {
        go_up(u);
        go_up(v);
    }

    return edges;
}

std::vector<int> find_roads(int n, std::vector<int> u, std::vector<int> v) {
    auto edge_str = [&](int e) {
        return to_string(u[e]) + " - " + to_string(v[e]) + " idx: " + to_string(e);
    };

    N = n;
    M = u.size();

    adj.resize(N, vector<int>{});
    eidx.resize(N, vector<int>(N, -1));
    par.resize(N, -1);
    used.resize(N, 0);
    depth.resize(N, 0);
    
    is_tree.resize(M, 0);
    status.resize(M, -1);
    added.resize(M, 0);

    for (int i = 0; i < M; i++) {
        eidx[ u[i] ][ v[i] ] = eidx[ v[i] ][ u[i] ] = i;
        adj[ u[i] ].push_back( v[i] );
        adj[ v[i] ].push_back( u[i] );
    }

    // 1. Find DFS tree
    dfs(0, 0);

    assert(tree_idx.size() == N - 1);
    assert(tree_idx.size() + back_idx.size() == M);
    assert(all_idx.size() == M);

    // cerr << "tree edges:\n";
    for (auto e : tree_idx) {
        // cerr << edge_str(e) << "\n";
        assert(status[e] == -1);
    }

    // 50 points

    int tree_ans = count_common_roads(tree_idx);
    // cerr << "tree_ans: " << tree_ans << "\n";

    // 2. Find status of all edges in tree_idx

    auto replace = [] (int e, int c, vector<int>& query) {
        auto p = find(query.begin(), query.end(), c);
        assert(p != query.end());
        *p = e;
    };

    for (auto e : back_idx) {
        // get cycle
        auto cycle = get_cycle(u[e], v[e]);
        int unknown = 0;
        for (auto c : cycle)
            unknown += (status[c] == -1);

        // cerr << "Back edge: " << edge_str(e) << "\n";
        // cerr << "cycle\n";
        // for (auto c : cycle) {
        //     cerr << edge_str(c) << "\n";
        // }

        auto replace_and_query = [&] (int e, int c) {
            auto query = tree_idx;
            replace(e, c, query);
            Q++;
            return count_common_roads(query) - tree_ans;
        };  

        if (!unknown) { // all is known
            // Just 1 query needed but useless since we want to find out tree_idx
            //status[e] = replace_and_query(e, cycle[0]) + status[cycle[0]];
            continue;
        } else if (unknown < cycle.size()) { // at least one is known
            // cerr << "at least one is known\n";
            // <= C++14
            int cand = -1;
            for (auto c : cycle) {
                if (status[c] != -1) {
                    cand = c;
                    break;
                }
            }

            status[e] = replace_and_query(e, cand) + status[cand];

            // use this to find the unknowns
            for (auto c : cycle) {
                if (status[c] == -1) {
                    status[c] = -replace_and_query(e, c) + status[e];
                }
            }
        } else { // all is unknown
            // cerr << "all is unknown\n";

            int neg = 0;
            int pos = 0;

            for (auto c : cycle) {
                status[c] = replace_and_query(e, c);
                // cerr << edge_str(c) << " delta: " << status[c] << "\n";
                neg += (status[c] < 0);
                pos += (status[c] > 0);
            }

            if (!pos && !neg) {
                // cerr << "nothing is different\n";
                assert (!pos);
                assert (!neg);
                for (auto c : cycle) {
                    status[c] = 0;
                }
                status[e] = 0;
            } else {
                assert(!pos || !neg);
                if (pos) {
                    for (auto c : cycle) {
                        status[c] = 1 - status[c];
                    }
                    status[e] = 1;
                    // cerr << "positive e\n";
                } else {
                    for (auto c : cycle) {
                        status[c] = -status[c];
                    }
                    status[e] = 0;
                    // cerr << "negative e\n";
                }

                // cerr << "find out\n";
                // for (auto c : cycle) {
                //     cerr << edge_str(c) << " -> " << status[c] << "\n";
                // }
                // cerr << "\n";
            }
        }
    }

    for (auto e : tree_idx) {
        if (status[e] == -1) {
            status[e] = 1;
        }
    }

    cerr << "first phase Q: " << Q << "\n";

    // 3. Binary search to find remaining edges

    vector<int> end_point(M);

    for (int n = 0; n < N; n++) {
        redo_par(n, n);

        vector<int> cand_idx;
        
        for (int j = 0; j < N; j++) {
            if (eidx[n][j] == -1)
                continue; 
            assert(j != n);
            int e = get(n, j);
            if (status[e] == -1 && !is_tree[e]) {
                cand_idx.push_back(e);
                end_point[e] = j;
            } 
        }
        if (!cand_idx.size())
            continue;

        // auto multi_query = [&](const vector<int> & qset) {
        //     auto query = tree_idx;
        //     int delta = 0;
        //     for (auto e : qset) {
        //         int re = get(end_point[e], par[end_point[e]]);
        //         assert(status[re] != -1);
        //         delta -= status[re];
        //         replace(e, re, query);
        //     }
        //     return count_common_roads(query) - (tree_ans + delta);
        // };

        auto multi_query = [&](int l, int r) {
            auto query = tree_idx;
            int delta = 0;
            for (int i = l; i <= r; i++) {
                auto e = cand_idx[i];

                int re = get(end_point[e], par[end_point[e]]);
                assert(status[re] != -1);
                delta -= status[re];
                replace(e, re, query);
            }
            Q++;
            return count_common_roads(query) - (tree_ans + delta);
        };


        auto full_ans = multi_query(0, cand_idx.size() - 1);
    
        function<void(int, int, int)> Rec = [&] (int l, int r, int tot) {
            int m = (l + r) >> 1;
            int sz = (r - l + 1);

            int left_ans = multi_query(l, m);

            int right_ans = tot - left_ans;

            auto Continue = [&] (int l1, int r1, int ans) {
                int sz = r1 - l1 + 1;

                if (!ans) {
                    for (int i = l1; i <= r1; i++) {
                        status[cand_idx[i]] = 0;
                    }
                    return false;
                } else if (ans == sz) {
                    for (int i = l1; i <= r1; i++) {
                        status[cand_idx[i]] = 1;
                    }
                    return false;
                } else {
                    return true;
                }
            };

            if (Continue(l, m, left_ans)) {
                Rec(l, m, left_ans);
            }
            if (Continue(m + 1, r, right_ans)) {
                Rec(m + 1, r, right_ans);
            }
        };

        // REDO
        if (!full_ans) {
            for (auto e : cand_idx)
                status[e] = 0;
        } else if (full_ans == cand_idx.size()) {
            for (auto e : cand_idx)
                status[e] = 1;
        } else {
            Rec(0, cand_idx.size() - 1, full_ans);
        }
    }

    cerr << "second phase Q: " << Q << "\n";

    vector<int> res;

    for (auto e : all_idx) {
        if (status[e] == 1) {
            res.push_back(e);
        }
    }

    assert(res.size() == N - 1);

    return res;
}

Compilation message

In file included from /usr/include/c++/10/cassert:44,
                 from simurgh.cpp:16:
simurgh.cpp: In function 'std::vector<int> find_roads(int, std::vector<int>, std::vector<int>)':
simurgh.cpp:133:28: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  133 |     assert(tree_idx.size() == N - 1);
      |            ~~~~~~~~~~~~~~~~^~~~~~~~
simurgh.cpp:134:46: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  134 |     assert(tree_idx.size() + back_idx.size() == M);
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
simurgh.cpp:135:27: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  135 |     assert(all_idx.size() == M);
      |            ~~~~~~~~~~~~~~~^~~~
simurgh.cpp:180:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  180 |         } else if (unknown < cycle.size()) { // at least one is known
      |                    ~~~~~~~~^~~~~~~~~~~~~~
simurgh.cpp: In lambda function:
simurgh.cpp:307:17: warning: unused variable 'sz' [-Wunused-variable]
  307 |             int sz = (r - l + 1);
      |                 ^~
simurgh.cpp: In function 'std::vector<int> find_roads(int, std::vector<int>, std::vector<int>)':
simurgh.cpp:343:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  343 |         } else if (full_ans == cand_idx.size()) {
      |                    ~~~~~~~~~^~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/10/cassert:44,
                 from simurgh.cpp:16:
simurgh.cpp:361:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  361 |     assert(res.size() == N - 1);
      |            ~~~~~~~~~~~^~~~~~~~
simurgh.cpp:107:10: warning: variable 'edge_str' set but not used [-Wunused-but-set-variable]
  107 |     auto edge_str = [&](int e) {
      |          ^~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB correct
2 Correct 0 ms 204 KB correct
3 Correct 0 ms 204 KB correct
4 Correct 0 ms 204 KB correct
5 Correct 0 ms 204 KB correct
6 Correct 0 ms 204 KB correct
7 Correct 1 ms 204 KB correct
8 Correct 0 ms 204 KB correct
9 Correct 0 ms 204 KB correct
10 Correct 1 ms 204 KB correct
11 Correct 1 ms 204 KB correct
12 Correct 0 ms 204 KB correct
13 Correct 0 ms 204 KB correct

Subtask #2
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB correct
2 Correct 0 ms 204 KB correct
3 Correct 0 ms 204 KB correct
4 Correct 0 ms 204 KB correct
5 Correct 0 ms 204 KB correct
6 Correct 0 ms 204 KB correct
7 Correct 1 ms 204 KB correct
8 Correct 0 ms 204 KB correct
9 Correct 0 ms 204 KB correct
10 Correct 1 ms 204 KB correct
11 Correct 1 ms 204 KB correct
12 Correct 0 ms 204 KB correct
13 Correct 0 ms 204 KB correct
14 Correct 2 ms 332 KB correct
15 Correct 2 ms 332 KB correct
16 Correct 1 ms 332 KB correct
17 Correct 1 ms 332 KB correct
18 Correct 1 ms 332 KB correct
19 Correct 1 ms 332 KB correct
20 Correct 1 ms 332 KB correct
21 Correct 1 ms 332 KB correct
22 Correct 1 ms 332 KB correct
23 Correct 1 ms 332 KB correct
24 Correct 1 ms 332 KB correct
25 Correct 0 ms 204 KB correct
26 Correct 1 ms 332 KB correct
27 Correct 1 ms 332 KB correct
28 Correct 1 ms 204 KB correct
29 Correct 1 ms 204 KB correct
30 Correct 1 ms 332 KB correct
31 Correct 1 ms 332 KB correct
32 Correct 1 ms 332 KB correct
33 Correct 1 ms 332 KB correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB correct
2 Correct 0 ms 204 KB correct
3 Correct 0 ms 204 KB correct
4 Correct 0 ms 204 KB correct
5 Correct 0 ms 204 KB correct
6 Correct 0 ms 204 KB correct
7 Correct 1 ms 204 KB correct
8 Correct 0 ms 204 KB correct
9 Correct 0 ms 204 KB correct
10 Correct 1 ms 204 KB correct
11 Correct 1 ms 204 KB correct
12 Correct 0 ms 204 KB correct
13 Correct 0 ms 204 KB correct
14 Correct 2 ms 332 KB correct
15 Correct 2 ms 332 KB correct
16 Correct 1 ms 332 KB correct
17 Correct 1 ms 332 KB correct
18 Correct 1 ms 332 KB correct
19 Correct 1 ms 332 KB correct
20 Correct 1 ms 332 KB correct
21 Correct 1 ms 332 KB correct
22 Correct 1 ms 332 KB correct
23 Correct 1 ms 332 KB correct
24 Correct 1 ms 332 KB correct
25 Correct 0 ms 204 KB correct
26 Correct 1 ms 332 KB correct
27 Correct 1 ms 332 KB correct
28 Correct 1 ms 204 KB correct
29 Correct 1 ms 204 KB correct
30 Correct 1 ms 332 KB correct
31 Correct 1 ms 332 KB correct
32 Correct 1 ms 332 KB correct
33 Correct 1 ms 332 KB correct
34 Correct 58 ms 1800 KB correct
35 Correct 59 ms 1796 KB correct
36 Correct 42 ms 1564 KB correct
37 Correct 9 ms 624 KB correct
38 Correct 59 ms 1820 KB correct
39 Correct 52 ms 1696 KB correct
40 Correct 63 ms 1484 KB correct
41 Correct 64 ms 1868 KB correct
42 Correct 61 ms 1796 KB correct
43 Correct 26 ms 1336 KB correct
44 Correct 22 ms 1140 KB correct
45 Correct 24 ms 1148 KB correct
46 Correct 18 ms 1044 KB correct
47 Correct 10 ms 716 KB correct
48 Correct 3 ms 460 KB correct
49 Correct 6 ms 588 KB correct
50 Correct 11 ms 716 KB correct
51 Correct 24 ms 1200 KB correct
52 Correct 23 ms 1136 KB correct
53 Correct 22 ms 1100 KB correct
54 Correct 27 ms 1332 KB correct
55 Correct 40 ms 1228 KB correct
56 Correct 29 ms 1220 KB correct
57 Correct 29 ms 1204 KB correct

Subtask #4
19.0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 204 KB correct
2 Correct 0 ms 204 KB correct
3 Correct 251 ms 4620 KB correct
4 Correct 566 ms 7680 KB correct
5 Correct 475 ms 7680 KB correct
6 Correct 518 ms 7740 KB correct
7 Correct 445 ms 7740 KB correct
8 Correct 518 ms 7844 KB correct
9 Correct 485 ms 7788 KB correct
10 Correct 480 ms 7720 KB correct
11 Correct 461 ms 7880 KB correct
12 Correct 465 ms 7692 KB correct
13 Correct 0 ms 204 KB correct
14 Correct 445 ms 7776 KB correct
15 Correct 475 ms 7872 KB correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB correct
2 Correct 0 ms 204 KB correct
3 Correct 0 ms 204 KB correct
4 Correct 0 ms 204 KB correct
5 Correct 0 ms 204 KB correct
6 Correct 0 ms 204 KB correct
7 Correct 1 ms 204 KB correct
8 Correct 0 ms 204 KB correct
9 Correct 0 ms 204 KB correct
10 Correct 1 ms 204 KB correct
11 Correct 1 ms 204 KB correct
12 Correct 0 ms 204 KB correct
13 Correct 0 ms 204 KB correct
14 Correct 2 ms 332 KB correct
15 Correct 2 ms 332 KB correct
16 Correct 1 ms 332 KB correct
17 Correct 1 ms 332 KB correct
18 Correct 1 ms 332 KB correct
19 Correct 1 ms 332 KB correct
20 Correct 1 ms 332 KB correct
21 Correct 1 ms 332 KB correct
22 Correct 1 ms 332 KB correct
23 Correct 1 ms 332 KB correct
24 Correct 1 ms 332 KB correct
25 Correct 0 ms 204 KB correct
26 Correct 1 ms 332 KB correct
27 Correct 1 ms 332 KB correct
28 Correct 1 ms 204 KB correct
29 Correct 1 ms 204 KB correct
30 Correct 1 ms 332 KB correct
31 Correct 1 ms 332 KB correct
32 Correct 1 ms 332 KB correct
33 Correct 1 ms 332 KB correct
34 Correct 58 ms 1800 KB correct
35 Correct 59 ms 1796 KB correct
36 Correct 42 ms 1564 KB correct
37 Correct 9 ms 624 KB correct
38 Correct 59 ms 1820 KB correct
39 Correct 52 ms 1696 KB correct
40 Correct 63 ms 1484 KB correct
41 Correct 64 ms 1868 KB correct
42 Correct 61 ms 1796 KB correct
43 Correct 26 ms 1336 KB correct
44 Correct 22 ms 1140 KB correct
45 Correct 24 ms 1148 KB correct
46 Correct 18 ms 1044 KB correct
47 Correct 10 ms 716 KB correct
48 Correct 3 ms 460 KB correct
49 Correct 6 ms 588 KB correct
50 Correct 11 ms 716 KB correct
51 Correct 24 ms 1200 KB correct
52 Correct 23 ms 1136 KB correct
53 Correct 22 ms 1100 KB correct
54 Correct 27 ms 1332 KB correct
55 Correct 40 ms 1228 KB correct
56 Correct 29 ms 1220 KB correct
57 Correct 29 ms 1204 KB correct
58 Correct 1 ms 204 KB correct
59 Correct 0 ms 204 KB correct
60 Correct 251 ms 4620 KB correct
61 Correct 566 ms 7680 KB correct
62 Correct 475 ms 7680 KB correct
63 Correct 518 ms 7740 KB correct
64 Correct 445 ms 7740 KB correct
65 Correct 518 ms 7844 KB correct
66 Correct 485 ms 7788 KB correct
67 Correct 480 ms 7720 KB correct
68 Correct 461 ms 7880 KB correct
69 Correct 465 ms 7692 KB correct
70 Correct 0 ms 204 KB correct
71 Correct 445 ms 7776 KB correct
72 Correct 475 ms 7872 KB correct
73 Correct 0 ms 288 KB correct
74 Correct 474 ms 7728 KB correct
75 Correct 453 ms 7580 KB correct
76 Correct 169 ms 3508 KB correct
77 Correct 488 ms 7732 KB correct
78 Correct 487 ms 7804 KB correct
79 Correct 454 ms 7780 KB correct
80 Correct 463 ms 7536 KB correct
81 Correct 381 ms 6840 KB correct
82 Correct 444 ms 7604 KB correct
83 Correct 249 ms 4828 KB correct
84 Correct 226 ms 5560 KB correct
85 Correct 198 ms 5124 KB correct
86 Correct 130 ms 3620 KB correct
87 Correct 111 ms 3228 KB correct
88 Correct 90 ms 2628 KB correct
89 Correct 79 ms 2628 KB correct
90 Correct 72 ms 2496 KB correct
91 Correct 28 ms 1460 KB correct
92 Correct 11 ms 1356 KB correct
93 Correct 199 ms 5076 KB correct
94 Correct 147 ms 3736 KB correct
95 Correct 131 ms 3556 KB correct
96 Correct 72 ms 2508 KB correct
97 Correct 106 ms 2708 KB correct
98 Correct 100 ms 3212 KB correct
99 Correct 96 ms 2608 KB correct
100 Correct 37 ms 1612 KB correct
101 Correct 13 ms 1328 KB correct
102 Correct 249 ms 4704 KB correct
103 Correct 231 ms 4624 KB correct
104 Correct 262 ms 4532 KB correct
105 Correct 246 ms 4540 KB correct