oj.uz

Submission #710767

# Submission time Handle Problem Language Result Execution time Memory
710767 2023-03-15T18:10:43 Z Jarif_Rahman Thousands Islands (IOI22_islands) C++17
100 / 100
 536 ms 52356 KB 
#include "islands.h"
#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;

int n, m;
vector<int> U, V;
vector<vector<int>> initial_graph, initial_graph_r;
vector<bool> reachable;

vector<set<int>> in(n), out(n);
set<pair<int, int>> st;

void dfs_reachability(int nd){
    if(reachable[nd]) return;
    reachable[nd] = 1;
    for(int x: initial_graph[nd]) dfs_reachability(x);
}

void remove_node(int nd){
    st.erase({out[nd].size(), nd});

    for(int i: in[nd]){
        st.erase({out[U[i]].size(), U[i]});
        out[U[i]].erase(i);
        st.insert({out[U[i]].size(), U[i]});
    }
    for(int i: out[nd]) in[V[i]].erase(i);
    out[nd].clear();
    in[nd].clear();
}

void preprocess(){
    in.resize(n);
    out.resize(n);
    for(int i = 0; i < m; i++){
        if(!reachable[U[i]] || !reachable[V[i]]) continue;
        out[U[i]].insert(i);
        in[V[i]].insert(i);
    }

    for(int i = 0; i < n; i++){
        st.insert({out[i].size(), i});
    }

    while(!st.empty() && st.begin()->f == 0) remove_node(st.begin()->sc);
}

vector<int> path_from_0(int nd){
    vector<int> dis(n, -1);
    queue<int> Q;
    dis[0] = 0;
    Q.push(0);
    while(!Q.empty()){
        int nd = Q.front(); Q.pop();
        for(int x: initial_graph[nd]) if(dis[x] == -1){
            dis[x] = dis[nd]+1;
            Q.push(x);
        }
    }

    vector<int> path;
    while(nd != 0){
        for(int i: initial_graph_r[nd]) if(dis[U[i]] == dis[nd]-1){
            path.pb(i);
            nd = U[i];
            break;
        }
    }

    reverse(path.begin(), path.end());
    return path;
}

vector<bool> bl;
vector<int> cycle, to_cycle, cycle_nd;
bool found = 0;
void dfs(int nd, int i){
    if(found) return;
    if(bl[nd]){
        while(cycle_nd.back() != nd){
            cycle.pb(to_cycle.back());
            to_cycle.pop_back();
            cycle_nd.pop_back();
        }
        reverse(cycle.begin(), cycle.end());
        cycle.pb(i);
        found = 1;
        return;
    }
    bl[nd] = 1;
    to_cycle.pb(i);
    cycle_nd.pb(nd);

    for(int j: out[nd]) dfs(V[j], j);
    if(!found){
        to_cycle.pop_back();
        cycle_nd.pop_back();
    }
}

vector<int> path2;
vector<bool> cycle_bl;
void dfs2(int nd, int i){
    if(found) return;
    if(bl[nd]) return;
    bl[nd] = 1;

    path2.pb(i);
    if(cycle_bl[nd]){
        found = 1;
        return;
    }

    for(int j: out[nd]) dfs2(V[j], j);
    if(!found){
        path2.pop_back();
    }
}


variant<bool, vector<int>> find_journey(int _n, int _m, vector<int> _U, vector<int> _V){
    n = _n, m = _m, U = _U, V = _V;

    initial_graph.assign(n, {});
    initial_graph_r.assign(n, {});
    reachable.assign(n, 0);

    for(int i = 0; i < m; i++) initial_graph[U[i]].pb(V[i]), initial_graph_r[V[i]].pb(i);

    dfs_reachability(0);
    preprocess();

    set<int> cur = {0};

    int ND = -1;
    while(!cur.empty()){
        for(int x: cur){
            if(out[x].size() >= 2) ND = x;
        }
        if(ND != -1) break;
        set<int> _cur;
        for(int x: cur) for(int i: out[x]) _cur.insert(V[i]);
        for(int x: cur) remove_node(x);
        while(!st.empty() && st.begin()->f == 0) remove_node(st.begin()->sc);
        swap(cur, _cur);
    }


    if(ND == -1) return false;

    auto p1 = path_from_0(ND);

    found = 0, cycle = {}, to_cycle = {}, cycle_nd = {ND};
    bl.assign(n, 0);
    bl[ND] = 1;
    dfs(V[*out[ND].begin()], *out[ND].begin());
    auto p2 = to_cycle, c1 = cycle;

    cycle_bl.assign(n, 0);
    for(int i: c1) cycle_bl[U[i]] = 1, cycle_bl[V[i]] = 1;
    bl.assign(n, 0);
    found = 0;
    dfs2(V[*next(out[ND].begin())], *next(out[ND].begin()));

    vector<int> ans;

    if(found){
        ans.insert(ans.end(), p1.begin(), p1.end());
        ans.insert(ans.end(), p2.begin(), p2.end());
        ans.insert(ans.end(), c1.begin(), c1.end());
        ans.insert(ans.end(), p2.rbegin(), p2.rend());
        ans.insert(ans.end(), path2.begin(), path2.end());

        int k = -1;
        for(int i = 0; i < c1.size(); i++) if(V[c1[i]] == V[path2.back()]) k = i;
        for(int i = 0; i < c1.size(); i++) ans.pb(c1[int(int(k+c1.size())-i)%int(c1.size())]);

        ans.insert(ans.end(), path2.rbegin(), path2.rend());
        ans.insert(ans.end(), p1.rbegin(), p1.rend());
        return ans;
    }

    found = 0, cycle = {}, to_cycle = {}, cycle_nd = {ND};
    bl.assign(n, 0);
    bl[ND] = 1;
    dfs(V[*next(out[ND].begin())], *next(out[ND].begin()));
    auto p3 = to_cycle, c2 = cycle;

    ans.insert(ans.end(), p1.begin(), p1.end());
    ans.insert(ans.end(), p2.begin(), p2.end());
    ans.insert(ans.end(), c1.begin(), c1.end());
    ans.insert(ans.end(), p2.rbegin(), p2.rend());
    ans.insert(ans.end(), p3.begin(), p3.end());
    ans.insert(ans.end(), c2.begin(), c2.end());
    ans.insert(ans.end(), p3.rbegin(), p3.rend());
    ans.insert(ans.end(), p2.begin(), p2.end());
    ans.insert(ans.end(), c1.rbegin(), c1.rend());
    ans.insert(ans.end(), p2.rbegin(), p2.rend());
    ans.insert(ans.end(), p3.begin(), p3.end());
    ans.insert(ans.end(), c2.rbegin(), c2.rend());
    ans.insert(ans.end(), p3.rbegin(), p3.rend());
    ans.insert(ans.end(), p1.rbegin(), p1.rend());

    return ans;
}

Compilation message

islands.cpp: In function 'std::variant<bool, std::vector<int, std::allocator<int> > > find_journey(int, int, std::vector<int>, std::vector<int>)':
islands.cpp:180:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  180 |         for(int i = 0; i < c1.size(); i++) if(V[c1[i]] == V[path2.back()]) k = i;
      |                        ~~^~~~~~~~~~~
islands.cpp:181:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  181 |         for(int i = 0; i < c1.size(); i++) ans.pb(c1[int(int(k+c1.size())-i)%int(c1.size())]);
      |                        ~~^~~~~~~~~~~

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 296 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 154 ms 25780 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 1 ms 212 KB Output is correct
3 Correct 1 ms 296 KB Output is correct
4 Correct 0 ms 304 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 175 ms 21164 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 1108 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 2 ms 212 KB Output is correct
5 Correct 2 ms 724 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 2 ms 432 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 1 ms 340 KB Output is correct
10 Correct 4 ms 728 KB Output is correct
11 Correct 1 ms 212 KB Output is correct
12 Correct 2 ms 724 KB Output is correct
13 Correct 1 ms 212 KB Output is correct
14 Correct 1 ms 212 KB Output is correct
15 Correct 1 ms 340 KB Output is correct
16 Correct 1 ms 340 KB Output is correct
17 Correct 96 ms 13740 KB Output is correct
18 Correct 72 ms 11424 KB Output is correct
19 Correct 1 ms 300 KB Output is correct
20 Correct 0 ms 212 KB Output is correct
21 Correct 1 ms 300 KB Output is correct
22 Correct 1 ms 212 KB Output is correct
23 Correct 193 ms 21384 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 696 KB Output is correct
3 Correct 140 ms 17368 KB Output is correct
4 Correct 148 ms 16936 KB Output is correct
5 Correct 4 ms 956 KB Output is correct
6 Correct 4 ms 992 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 2 ms 852 KB Output is correct
11 Correct 3 ms 980 KB Output is correct
12 Correct 4 ms 984 KB Output is correct
13 Correct 5 ms 1108 KB Output is correct
14 Correct 2 ms 952 KB Output is correct
15 Correct 5 ms 1292 KB Output is correct
16 Correct 3 ms 804 KB Output is correct
17 Correct 1 ms 212 KB Output is correct
18 Correct 3 ms 980 KB Output is correct
19 Correct 2 ms 596 KB Output is correct
20 Correct 280 ms 26420 KB Output is correct
21 Correct 134 ms 15632 KB Output is correct
22 Correct 3 ms 724 KB Output is correct
23 Correct 1 ms 468 KB Output is correct
24 Correct 1 ms 212 KB Output is correct
25 Correct 11 ms 468 KB Output is correct
26 Correct 2 ms 852 KB Output is correct
27 Correct 160 ms 19248 KB Output is correct
28 Correct 173 ms 19292 KB Output is correct
29 Correct 1 ms 212 KB Output is correct
30 Correct 299 ms 26296 KB Output is correct
31 Correct 1 ms 212 KB Output is correct
32 Correct 148 ms 18608 KB Output is correct
33 Correct 230 ms 25176 KB Output is correct
34 Correct 79 ms 13772 KB Output is correct
35 Correct 1 ms 564 KB Output is correct
36 Correct 121 ms 16280 KB Output is correct
37 Correct 214 ms 25456 KB Output is correct
38 Correct 1 ms 436 KB Output is correct
39 Correct 199 ms 20440 KB Output is correct
40 Correct 2 ms 724 KB Output is correct
41 Correct 324 ms 26320 KB Output is correct
42 Correct 163 ms 19276 KB Output is correct
43 Correct 1 ms 212 KB Output is correct
44 Correct 4 ms 980 KB Output is correct
45 Correct 2 ms 852 KB Output is correct
46 Correct 73 ms 11200 KB Output is correct

Subtask #5
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 296 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 154 ms 25780 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 296 KB Output is correct
11 Correct 0 ms 304 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 175 ms 21164 KB Output is correct
14 Correct 5 ms 1108 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 1 ms 212 KB Output is correct
17 Correct 2 ms 212 KB Output is correct
18 Correct 2 ms 724 KB Output is correct
19 Correct 1 ms 212 KB Output is correct
20 Correct 2 ms 432 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 1 ms 340 KB Output is correct
23 Correct 4 ms 728 KB Output is correct
24 Correct 1 ms 212 KB Output is correct
25 Correct 2 ms 724 KB Output is correct
26 Correct 1 ms 212 KB Output is correct
27 Correct 1 ms 212 KB Output is correct
28 Correct 1 ms 340 KB Output is correct
29 Correct 1 ms 340 KB Output is correct
30 Correct 96 ms 13740 KB Output is correct
31 Correct 72 ms 11424 KB Output is correct
32 Correct 1 ms 300 KB Output is correct
33 Correct 0 ms 212 KB Output is correct
34 Correct 1 ms 300 KB Output is correct
35 Correct 1 ms 212 KB Output is correct
36 Correct 193 ms 21384 KB Output is correct
37 Correct 1 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 2 ms 340 KB Output is correct
41 Correct 73 ms 8820 KB Output is correct
42 Correct 4 ms 852 KB Output is correct
43 Correct 206 ms 26516 KB Output is correct
44 Correct 188 ms 26056 KB Output is correct
45 Correct 187 ms 26576 KB Output is correct
46 Correct 1 ms 212 KB Output is correct
47 Correct 1 ms 300 KB Output is correct
48 Correct 1 ms 212 KB Output is correct
49 Correct 2 ms 688 KB Output is correct
50 Correct 242 ms 44420 KB Output is correct
51 Correct 409 ms 51620 KB Output is correct
52 Correct 403 ms 51832 KB Output is correct
53 Correct 416 ms 52356 KB Output is correct
54 Correct 454 ms 51356 KB Output is correct
55 Correct 399 ms 51784 KB Output is correct
56 Correct 389 ms 51488 KB Output is correct
57 Correct 196 ms 41072 KB Output is correct
58 Correct 205 ms 41520 KB Output is correct
59 Correct 536 ms 48756 KB Output is correct
60 Correct 207 ms 34640 KB Output is correct
61 Correct 128 ms 29244 KB Output is correct
62 Correct 27 ms 11260 KB Output is correct
63 Correct 131 ms 29084 KB Output is correct
64 Correct 101 ms 10276 KB Output is correct
65 Correct 1 ms 300 KB Output is correct
66 Correct 1 ms 340 KB Output is correct
67 Correct 283 ms 46128 KB Output is correct
68 Correct 368 ms 26632 KB Output is correct
69 Correct 158 ms 31564 KB Output is correct
70 Correct 2 ms 820 KB Output is correct
71 Correct 302 ms 31072 KB Output is correct
72 Correct 1 ms 212 KB Output is correct
73 Correct 491 ms 42040 KB Output is correct
74 Correct 237 ms 43584 KB Output is correct
75 Correct 9 ms 1728 KB Output is correct
76 Correct 77 ms 20872 KB Output is correct
77 Correct 215 ms 40704 KB Output is correct
78 Correct 214 ms 34508 KB Output is correct
79 Correct 1 ms 212 KB Output is correct
80 Correct 434 ms 46460 KB Output is correct
81 Correct 2 ms 724 KB Output is correct
82 Correct 232 ms 25956 KB Output is correct
83 Correct 2 ms 468 KB Output is correct
84 Correct 1 ms 212 KB Output is correct
85 Correct 90 ms 20900 KB Output is correct
86 Correct 3 ms 852 KB Output is correct
87 Correct 29 ms 15180 KB Output is correct
88 Correct 5 ms 1128 KB Output is correct
89 Correct 198 ms 34452 KB Output is correct
90 Correct 118 ms 29352 KB Output is correct
91 Correct 391 ms 46352 KB Output is correct
92 Correct 1 ms 212 KB Output is correct