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Submission #695311

# Submission time Handle Problem Language Result Execution time Memory
695311 2023-02-05T01:07:50 Z 79brue Thousands Islands (IOI22_islands) C++17
100 / 100
 580 ms 51196 KB 
#include "islands.h"
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

void add(vector<int> &A, vector<int> &B, int rev = 0){
    if(!rev) for(auto x: B) A.push_back(x);
    else for(int i=(int)B.size()-1; i>=0; i--) A.push_back(B[i]);
}

int n, m;
multiset<int> link[100002], revLink[100002];

bool removeUselessVertices();
vector<int> solve();

multimap<pair<int, int>, int> edgeMap;
multimap<pair<int, int>, int> edgeMap2;

variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V){
    n = N, m = M;
    for(int i=0; i<m; i++){
        link[U[i]].insert(V[i]);
        revLink[V[i]].insert(U[i]);
    }

    if(removeUselessVertices()) return false;
    vector<int> ret;
    vector<int> ans = solve();
    for(int i=0; i<m; i++) edgeMap.insert(make_pair(make_pair(U[i], V[i]), i));

    for(int i=0; i<(int)ans.size()-1; i++){
        int x = ans[i], y = ans[i+1];
        auto it = edgeMap2.find(make_pair(x, y));
        if(it != edgeMap2.end() && it->first == make_pair(x, y) &&
           (!(!ret.empty() && ret.back() == it->second) ||
            (next(it) != edgeMap2.end() && next(it)->first == make_pair(x, y)))){
            if(!ret.empty() && ret.back() == it->second) ++it;
            ret.push_back(it->second);
            edgeMap2.erase(it);
            edgeMap.insert(make_pair(make_pair(y, x), ret.back()));
        }
        else{
            it = edgeMap.find(make_pair(x, y));
            if(!ret.empty() && ret.back() == it->second) ++it;
            ret.push_back(it->second);
            edgeMap.erase(it);
            edgeMap2.insert(make_pair(make_pair(y, x), ret.back()));
        }
    }

    return ret;
}

int deg[100002];
bool removed[100002];
bool seenAsStart[100002];
int s = 0;
vector<int> startList;

bool removeUselessVertices(){
    /// outdegree 0 삭제
    queue<int> que;
    for(int i=0; i<n; i++){
        deg[i] = (int)link[i].size();
        if(!deg[i] && !removed[i]) removed[i] = 1, que.push(i);
    }
    while(deg[s] == 1){
        for(auto y: revLink[s]){
            link[y].erase(link[y].find(s));
            deg[y]--;
            if(!deg[y] && !removed[y]) removed[y] = 1, que.push(y);
        }
        revLink[s].clear();
        startList.push_back(s);
        int ns = *link[s].begin();
        link[s].erase(link[s].find(ns));
        revLink[ns].erase(revLink[ns].find(s));
        s = ns;
    }

    while(!que.empty()){
        int x = que.front(); que.pop();
        deg[x] = 0;
        if(x==s) return 1;
        for(auto y: revLink[x]){
            deg[y]--;
            link[y].erase(link[y].find(x));

            if(!deg[y] && !removed[y]) removed[y] = 1, que.push(y);
            while(deg[s] == 1){
                for(auto y: revLink[s]){
                    link[y].erase(link[y].find(s));
                    deg[y]--;
                    if(!deg[y] && !removed[y]) removed[y] = 1, que.push(y);
                }
                revLink[s].clear();
                startList.push_back(s);
                int ns = *link[s].begin();
                link[s].erase(link[s].find(ns));
                revLink[ns].erase(revLink[ns].find(s));
                s = ns;
                if(removed[ns]) return 1;
            }
        }
    }

    if(removed[s]) return true;
    return false;
}

int A = -1, B = -1;
bool visited[100002];
bool visitedinA[100002];
bool search_mode = 0;
bool search_overlap = 0;

void justSearch(int x){
    visited[x] = 1;
    if(search_mode == 0 && x != s) visitedinA[x] = 1;
    for(auto y: link[x]){
        if(x==s && y!=A && y!=B) continue;
        if(x==s && y==B) search_mode = 1;
        if(visited[y]){
            if(search_mode && visitedinA[y]) search_overlap = 1;
            continue;
        }
        justSearch(y);
    }
}

vector<int> rec;
bool findCycle(int x, int lead, vector<int> &path, vector<int> &cycle, bool ina=0){
    if(x==s) rec.clear();
    visited[x] = 1;
    rec.push_back(x);
    for(auto y: link[x]){
        if(x==s && y!=lead) continue;
        if(visited[y]){
            if(!ina || (y==0 && visitedinA[x]) || visitedinA[y]){
                int c = find(rec.begin(), rec.end(), y) - rec.begin();
                for(int i=0; i<=c; i++) path.push_back(rec[i]);
                for(int i=c+1; i<(int)rec.size(); i++) cycle.push_back(rec[i]);
                return true;
            }
            continue;
        }
        if(findCycle(y, lead, path, cycle, ina)) return true;
    }
    rec.pop_back();
    return false;
}

bool inCycle[100002];

vector<int> record;
bool findInCycle(int x, int lead, vector<int> &path){
    visited[x] = 1;
    record.push_back(x);

    for(auto y: link[x]){
        if(x==s && y!=lead) continue;
        if(inCycle[y] && y!=s){
            for(auto z: record){
                path.push_back(z);
            }
            path.push_back(y);
            return true;
        }
        if(visited[y]) continue;
        if(findInCycle(y, lead, path)) return true;
    }
    record.pop_back();
    return false;
}

vector<int> solve(){
    vector<int> ret;

    if((int)link[s].size() <= 1) exit(1);
    assert((int)link[s].size() > 1);
    A = *link[s].begin();
    B = *next(link[s].begin());

    justSearch(s);

    /// Case 2. A=B
    if(A==B){
        vector<int> pathA, cycleA;
        memset(visited, 0, sizeof(visited));
        findCycle(s, A, pathA, cycleA);
        cycleA.insert(cycleA.begin(), pathA.back());
        pathA.pop_back();

        if(find(cycleA.begin(), cycleA.end(), s) == cycleA.end()){ /// 시작점이 포함되지 않음
            int c = cycleA[0];
            add(ret, startList);
            add(ret, pathA); add(ret, cycleA); ret.push_back(c); add(ret, pathA, 1); ret.pop_back();
            add(ret, pathA); ret.push_back(c); add(ret, cycleA, 1); add(ret, pathA, 1);
            add(ret, startList, 1);
            return ret;
        }
        else{
            add(ret, startList);
            add(ret, pathA); add(ret, cycleA);
            ret.push_back(s);

            int idx = find(cycleA.begin(), cycleA.end(), B) - cycleA.begin();
            for(int i=idx; i>=0; i--) ret.push_back(cycleA[i]);
            for(int i=(int)cycleA.size()-1; i>=idx; i--) ret.push_back(cycleA[i]);

            ret.push_back(s);
            add(ret, startList, 1);
            return ret;
        }
    }

    /// Case 1. A -> B의 경로가 없다
    if(!visitedinA[B] && !search_overlap){
        /// 각각 사이클 찾기
        vector<int> pathA, cycleA, pathB, cycleB;
        memset(visited, 0, sizeof(visited));
        findCycle(s, A, pathA, cycleA);
        memset(visited, 0, sizeof(visited));
        findCycle(s, B, pathB, cycleB);

        add(ret, startList);

        add(ret, pathA);
        add(ret, cycleA);
        add(ret, pathA, 1);
        ret.pop_back();

        add(ret, pathB);
        add(ret, cycleB);
        add(ret, pathB, 1);
        ret.pop_back();

        add(ret, pathA);

        add(ret, cycleA, 1);
        add(ret, pathA, 1);
        ret.pop_back();

        add(ret, pathB);
        add(ret, cycleB, 1);
        add(ret, pathB, 1);

        add(ret, startList, 1);
        return ret;
    }

    /// Case 3. A->B의 경로가 있다
    vector<int> pathB, cycleB;
    memset(visited, 0, sizeof(visited));
    findCycle(s, B, pathB, cycleB, 1);

    cycleB.insert(cycleB.begin(), pathB.back());
    pathB.pop_back();

    if(find(cycleB.begin(), cycleB.end(), s) == cycleB.end()){ /// 시작점이 포함되지 않은 사이클
        for(auto x: cycleB) inCycle[x] = 1;

        add(ret, startList);
        add(ret, pathB);
        add(ret, cycleB);
        ret.push_back(cycleB[0]);
        add(ret, pathB, 1);

        vector<int> pathA;
        memset(visited, 0, sizeof(visited));
        findInCycle(s, A, pathA);

        int c = pathA.back();
        pathA.pop_back();

        ret.pop_back();
        add(ret, pathA);
        int idx = find(cycleB.begin(), cycleB.end(), c) - cycleB.begin();
        for(int i=idx; i>=0; i--) ret.push_back(cycleB[i]);
        for(int i=(int)cycleB.size()-1; i>=idx; i--) ret.push_back(cycleB[i]);
        add(ret, pathA, 1);
        add(ret, startList, 1);

        return ret;
    }

    /// 시작점이 포함된 사이클
    for(auto x: cycleB) inCycle[x] = 1;

    add(ret, startList);
    add(ret, cycleB);

    vector<int> pathA;
    memset(visited, 0, sizeof(visited));
    findInCycle(s, A, pathA);
    int c = pathA.back();
    pathA.pop_back();

    add(ret, pathA);
    int idx = find(cycleB.begin(), cycleB.end(), c) - cycleB.begin();
    for(int i=idx; i>=0; i--) ret.push_back(cycleB[i]);
    for(int i=(int)cycleB.size()-1; i>=idx; i--) ret.push_back(cycleB[i]);
    add(ret, pathA, 1);
    add(ret, startList, 1);

    return ret;
}

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9684 KB Output is correct
2 Correct 5 ms 9684 KB Output is correct
3 Correct 5 ms 9684 KB Output is correct
4 Correct 5 ms 9684 KB Output is correct
5 Correct 5 ms 9684 KB Output is correct
6 Correct 6 ms 9812 KB Output is correct
7 Correct 156 ms 44120 KB Output is correct

Subtask #2
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9684 KB Output is correct
2 Correct 4 ms 9684 KB Output is correct
3 Correct 5 ms 9704 KB Output is correct
4 Correct 4 ms 9812 KB Output is correct
5 Correct 5 ms 9736 KB Output is correct
6 Correct 198 ms 37312 KB Output is correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 10452 KB Output is correct
2 Correct 5 ms 9684 KB Output is correct
3 Correct 5 ms 9684 KB Output is correct
4 Correct 4 ms 9684 KB Output is correct
5 Correct 7 ms 9940 KB Output is correct
6 Correct 4 ms 9812 KB Output is correct
7 Correct 5 ms 9824 KB Output is correct
8 Correct 5 ms 9812 KB Output is correct
9 Correct 5 ms 9844 KB Output is correct
10 Correct 6 ms 10068 KB Output is correct
11 Correct 5 ms 9812 KB Output is correct
12 Correct 6 ms 9988 KB Output is correct
13 Correct 4 ms 9684 KB Output is correct
14 Correct 5 ms 9684 KB Output is correct
15 Correct 5 ms 9812 KB Output is correct
16 Correct 4 ms 9684 KB Output is correct
17 Correct 101 ms 27000 KB Output is correct
18 Correct 79 ms 23628 KB Output is correct
19 Correct 5 ms 9684 KB Output is correct
20 Correct 5 ms 9740 KB Output is correct
21 Correct 5 ms 9812 KB Output is correct
22 Correct 5 ms 9824 KB Output is correct
23 Correct 234 ms 37236 KB Output is correct

Subtask #4
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 9812 KB Output is correct
2 Correct 9 ms 10452 KB Output is correct
3 Correct 242 ms 40676 KB Output is correct
4 Correct 227 ms 40704 KB Output is correct
5 Correct 7 ms 10452 KB Output is correct
6 Correct 7 ms 10452 KB Output is correct
7 Correct 6 ms 9684 KB Output is correct
8 Correct 5 ms 9812 KB Output is correct
9 Correct 5 ms 9684 KB Output is correct
10 Correct 7 ms 10196 KB Output is correct
11 Correct 6 ms 10068 KB Output is correct
12 Correct 7 ms 10452 KB Output is correct
13 Correct 8 ms 10544 KB Output is correct
14 Correct 7 ms 10452 KB Output is correct
15 Correct 9 ms 10836 KB Output is correct
16 Correct 6 ms 10068 KB Output is correct
17 Correct 5 ms 9684 KB Output is correct
18 Correct 7 ms 10512 KB Output is correct
19 Correct 7 ms 10152 KB Output is correct
20 Correct 192 ms 31728 KB Output is correct
21 Correct 244 ms 40740 KB Output is correct
22 Correct 5 ms 9812 KB Output is correct
23 Correct 5 ms 9812 KB Output is correct
24 Correct 5 ms 9684 KB Output is correct
25 Correct 6 ms 10068 KB Output is correct
26 Correct 7 ms 10196 KB Output is correct
27 Correct 240 ms 42428 KB Output is correct
28 Correct 258 ms 42504 KB Output is correct
29 Correct 5 ms 9684 KB Output is correct
30 Correct 225 ms 31640 KB Output is correct
31 Correct 4 ms 9812 KB Output is correct
32 Correct 246 ms 40812 KB Output is correct
33 Correct 239 ms 42472 KB Output is correct
34 Correct 86 ms 27012 KB Output is correct
35 Correct 6 ms 10068 KB Output is correct
36 Correct 206 ms 37336 KB Output is correct
37 Correct 228 ms 42544 KB Output is correct
38 Correct 5 ms 9812 KB Output is correct
39 Correct 135 ms 26536 KB Output is correct
40 Correct 6 ms 10132 KB Output is correct
41 Correct 242 ms 31620 KB Output is correct
42 Correct 247 ms 42504 KB Output is correct
43 Correct 5 ms 9684 KB Output is correct
44 Correct 6 ms 10148 KB Output is correct
45 Correct 7 ms 10196 KB Output is correct
46 Correct 65 ms 23544 KB Output is correct

Subtask #5
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 9684 KB Output is correct
2 Correct 5 ms 9684 KB Output is correct
3 Correct 5 ms 9684 KB Output is correct
4 Correct 5 ms 9684 KB Output is correct
5 Correct 5 ms 9684 KB Output is correct
6 Correct 6 ms 9812 KB Output is correct
7 Correct 156 ms 44120 KB Output is correct
8 Correct 5 ms 9684 KB Output is correct
9 Correct 4 ms 9684 KB Output is correct
10 Correct 5 ms 9704 KB Output is correct
11 Correct 4 ms 9812 KB Output is correct
12 Correct 5 ms 9736 KB Output is correct
13 Correct 198 ms 37312 KB Output is correct
14 Correct 9 ms 10452 KB Output is correct
15 Correct 5 ms 9684 KB Output is correct
16 Correct 5 ms 9684 KB Output is correct
17 Correct 4 ms 9684 KB Output is correct
18 Correct 7 ms 9940 KB Output is correct
19 Correct 4 ms 9812 KB Output is correct
20 Correct 5 ms 9824 KB Output is correct
21 Correct 5 ms 9812 KB Output is correct
22 Correct 5 ms 9844 KB Output is correct
23 Correct 6 ms 10068 KB Output is correct
24 Correct 5 ms 9812 KB Output is correct
25 Correct 6 ms 9988 KB Output is correct
26 Correct 4 ms 9684 KB Output is correct
27 Correct 5 ms 9684 KB Output is correct
28 Correct 5 ms 9812 KB Output is correct
29 Correct 4 ms 9684 KB Output is correct
30 Correct 101 ms 27000 KB Output is correct
31 Correct 79 ms 23628 KB Output is correct
32 Correct 5 ms 9684 KB Output is correct
33 Correct 5 ms 9740 KB Output is correct
34 Correct 5 ms 9812 KB Output is correct
35 Correct 5 ms 9824 KB Output is correct
36 Correct 234 ms 37236 KB Output is correct
37 Correct 4 ms 9684 KB Output is correct
38 Correct 5 ms 9716 KB Output is correct
39 Correct 7 ms 9732 KB Output is correct
40 Correct 6 ms 9812 KB Output is correct
41 Correct 93 ms 19488 KB Output is correct
42 Correct 7 ms 10152 KB Output is correct
43 Correct 107 ms 20792 KB Output is correct
44 Correct 103 ms 20792 KB Output is correct
45 Correct 145 ms 27156 KB Output is correct
46 Correct 5 ms 9684 KB Output is correct
47 Correct 5 ms 9684 KB Output is correct
48 Correct 5 ms 9684 KB Output is correct
49 Correct 6 ms 10016 KB Output is correct
50 Correct 426 ms 32480 KB Output is correct
51 Correct 245 ms 32128 KB Output is correct
52 Correct 249 ms 32004 KB Output is correct
53 Correct 354 ms 44672 KB Output is correct
54 Correct 245 ms 32076 KB Output is correct
55 Correct 272 ms 32012 KB Output is correct
56 Correct 339 ms 44672 KB Output is correct
57 Correct 308 ms 43696 KB Output is correct
58 Correct 368 ms 36720 KB Output is correct
59 Correct 234 ms 34544 KB Output is correct
60 Correct 229 ms 34560 KB Output is correct
61 Correct 236 ms 34632 KB Output is correct
62 Correct 22 ms 13780 KB Output is correct
63 Correct 148 ms 33228 KB Output is correct
64 Correct 141 ms 25636 KB Output is correct
65 Correct 5 ms 9812 KB Output is correct
66 Correct 6 ms 9940 KB Output is correct
67 Correct 280 ms 48364 KB Output is correct
68 Correct 274 ms 33100 KB Output is correct
69 Correct 111 ms 22624 KB Output is correct
70 Correct 7 ms 10196 KB Output is correct
71 Correct 155 ms 28024 KB Output is correct
72 Correct 6 ms 9812 KB Output is correct
73 Correct 225 ms 34320 KB Output is correct
74 Correct 302 ms 36836 KB Output is correct
75 Correct 13 ms 11388 KB Output is correct
76 Correct 107 ms 23256 KB Output is correct
77 Correct 100 ms 22856 KB Output is correct
78 Correct 242 ms 34556 KB Output is correct
79 Correct 6 ms 9704 KB Output is correct
80 Correct 580 ms 51196 KB Output is correct
81 Correct 7 ms 10068 KB Output is correct
82 Correct 188 ms 32372 KB Output is correct
83 Correct 6 ms 9880 KB Output is correct
84 Correct 5 ms 9872 KB Output is correct
85 Correct 127 ms 22676 KB Output is correct
86 Correct 7 ms 10104 KB Output is correct
87 Correct 7 ms 10580 KB Output is correct
88 Correct 9 ms 10648 KB Output is correct
89 Correct 239 ms 34560 KB Output is correct
90 Correct 222 ms 34528 KB Output is correct
91 Correct 498 ms 49660 KB Output is correct
92 Correct 5 ms 9684 KB Output is correct