Submission #579908

#	Time	Username	Problem	Language	Result	Execution time	Memory
579908		drdilyor	Love Polygon (BOI18_polygon)	C++17	100 / 100	389 ms	33276 KiB

polygon

#if defined(ONPC) && !defined(_GLIBCXX_ASSERTIONS)
    #define _GLIBCXX_ASSERTIONS
#endif
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/detail/standard_policies.hpp>
#define cerr cout
#ifdef ONPC
    #include "t_debug.cpp"
#else
    #define debug(...) 42
#endif
#define allit(a) (a).begin(), (a).end()
#define sz(a) ((int) (a).size())

using namespace std;
using ll = long long;
using vi = vector<int>;
namespace pd = __gnu_pbds;
template<typename K>
using ordered_set = pd::tree<K, pd::null_type, less<int>, pd::rb_tree_tag, pd::tree_order_statistics_node_update>;
template<typename... T>
using gp_hash_table = pd::gp_hash_table<T...>;//simple using statement gives warnings

const int INF = 1e9;
const ll INFL = 1e18;
const int N = 1e5;
const int RANDOM = chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937 rng(RANDOM);

int ans;
void confirm(int i) {
#ifdef ONPC
    if (i == ans) cout << "ok " << i << endl;
    else cout << "wrong " << i << ", expected " << ans << endl;
#else
    cout << i << '\n';
#endif
}

int solve() {
    int n; cin >> n;
    map<string, int> code;
    vector<string> name(n);

    vi adj(n);
    vector<set<int>> rev(n);

    for (int i = 0, t = 0; i < n; i++) {
        string u, v;
        cin >> u >> v;
        if (code.count(u) == 0) {
            name[t] = u;
            code[u] = t++;
        }
        if (code.count(v) == 0) {
            name[t] = v;
            code[v] = t++;
        }
        adj[code[u]] = code[v];
        rev[code[v]].insert(code[u]);
    }

    if (n % 2 == 1) {confirm(-1); return 0;}

    vi inrel(n);
    int inrel_count = 0;
    for (int i = 0; i <n; i++) {
        inrel_count += inrel[i] = (
            i != adj[i] && adj[adj[i]] == i);
    }
    debug(name);
    debug(adj, rev, inrel);


    int res = 0;
    //unloved ones shall be matched
    {
        set<int> unloved;
        auto set_love = [&](int from, int to) {
            rev[adj[from]].erase(from);
            rev[to].insert(from);
            adj[from] = to;
        };
        auto check = [&](int i) {
            if (rev[i].empty()) {
                if (inrel[adj[i]]) {set_love(i, i); return false; }
                else {unloved.insert(i); return true; }
            }
            return false;
        };
        function<void()> action = [&]() {
            for (int i = 0; i < n; i++) {
                check(i);
            }

            while (!unloved.empty()) {
                int i = *unloved.begin();
                if (check(i)) {
                    int j = adj[i];
                    // remove those who love j
                    for (int k : rev[j]) {
                        adj[k] = k;
                        rev[k].insert(k);
                    }
                    int dangling = adj[j];
                    rev[j].clear();
                    set_love(j, i);
                    set_love(i, j);
                    inrel[j] = inrel[i] = 1;
                    inrel_count += 2;
                    res++;
                    check(dangling);
                }
                debug(i, adj, rev, inrel, unloved);
                unloved.erase(i);
            }
        };

        action();
        vi adj_p = adj;
        debug("run 2");
        action();
        assert(adj == adj_p);

        for (int i = 0; i < n; i++) {
            assert(rev[i].size() == 1);
        }
    }
    debug(res);
    // polygons shall no longer survive
    if (inrel_count != n) {
        vi visited(n, 0);
        auto cycle = [&](int i, int depth) {
            res += (depth + 1) / 2;
            debug("cycle", i, depth);
        };
        function<pair<int,int>(int)> dfs = [&](int i) -> pair<int,int> {
            if (inrel[i]) return {-1, -1};
            if (visited[i]) { return {i, 0}; }
            debug("dfs", i);
            visited[i] = 1;
            auto [end, depth] = dfs(adj[i]);
            if (end == -1) return {-1, -1};
            depth++;

            inrel[i] = 1;
            if (end == i) {
                cycle(end, depth);
                assert(depth != 2);
                return {-1, -1};
            }
            return {end, depth};
        };
        for (int i = 0; i < n; i++) {
            if (!inrel[i] && !visited[i]) {
                auto [end, depth] = dfs(i);
                if (end != -1) cycle(end, depth);
            }
        }
    }
    confirm(res);

    return 0;
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
#ifdef ONPC
    cin >> t;
    while (t-- && cin) {
        cin >> ans;
        if (!cin) break;
#else
    while (t-- && cin) {
#endif
        if (solve()) break;
        #ifdef ONPC
            cout << "____________________" << endl;
        #endif
    }
    return 0;
}

Compilation message (stderr)

polygon.cpp: In function 'int solve()':
polygon.cpp:11:24: warning: statement has no effect [-Wunused-value]
   11 |     #define debug(...) 42
      |                        ^~
polygon.cpp:72:5: note: in expansion of macro 'debug'
   72 |     debug(name);
      |     ^~~~~
polygon.cpp:11:24: warning: statement has no effect [-Wunused-value]
   11 |     #define debug(...) 42
      |                        ^~
polygon.cpp:73:5: note: in expansion of macro 'debug'
   73 |     debug(adj, rev, inrel);
      |     ^~~~~
polygon.cpp: In lambda function:
polygon.cpp:11:24: warning: statement has no effect [-Wunused-value]
   11 |     #define debug(...) 42
      |                        ^~
polygon.cpp:115:17: note: in expansion of macro 'debug'
  115 |                 debug(i, adj, rev, inrel, unloved);
      |                 ^~~~~
polygon.cpp: In function 'int solve()':
polygon.cpp:11:24: warning: statement has no effect [-Wunused-value]
   11 |     #define debug(...) 42
      |                        ^~
polygon.cpp:122:9: note: in expansion of macro 'debug'
  122 |         debug("run 2");
      |         ^~~~~
polygon.cpp:11:24: warning: statement has no effect [-Wunused-value]
   11 |     #define debug(...) 42
      |                        ^~
polygon.cpp:130:5: note: in expansion of macro 'debug'
  130 |     debug(res);
      |     ^~~~~
polygon.cpp: In lambda function:
polygon.cpp:11:24: warning: statement has no effect [-Wunused-value]
   11 |     #define debug(...) 42
      |                        ^~
polygon.cpp:136:13: note: in expansion of macro 'debug'
  136 |             debug("cycle", i, depth);
      |             ^~~~~
polygon.cpp: In lambda function:
polygon.cpp:11:24: warning: statement has no effect [-Wunused-value]
   11 |     #define debug(...) 42
      |                        ^~
polygon.cpp:141:13: note: in expansion of macro 'debug'
  141 |             debug("dfs", i);
      |             ^~~~~

• Subtask 1: 21 / 21
• Subtask 2: 25 / 25
• Subtask 3: 29 / 29
• Subtask 4: 25 / 25