Submission #1182121

#	Time	Username	Problem	Language	Result	Execution time	Memory
1182121		Mher777	Love Polygon (BOI18_polygon)	C++20	54 / 100	215 ms	26056 KiB

polygon

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <array>
#include <string>
#include <algorithm>
#include <cmath>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <iterator>
#include <numeric>
#include <complex>
#include <utility>
#include <random>
#include <cassert>
#include <fstream>
using namespace std;
mt19937 rnd(time(nullptr));

/* -------------------- Typedefs -------------------- */

typedef int itn;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef float fl;
typedef long double ld;

/* -------------------- Usings -------------------- */

using vi = vector<int>;
using vll = vector<ll>;
using mii = map<int, int>;
using mll = map<ll, ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

/* -------------------- Defines -------------------- */

#define ff first
#define ss second
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
#define mpr make_pair
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define all(x) (x).begin(), (x).end()
#define USACO freopen("feast.in", "r", stdin); freopen("feast.out", "w", stdout);

/* -------------------- Constants -------------------- */

const int dx[8] = { -1, 0, 1, 0, -1, -1, 1, 1 };
const int dy[8] = { 0, -1, 0, 1, -1, 1, -1, 1 };
const int MAX = int(1e9 + 5);
const ll MAXL = ll(1e18) + 5ll;
const ll MOD = ll(1000000007);
const ll MOD2 = ll(998244353);

/* -------------------- Functions -------------------- */

void fastio() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
}

void precision(int x) {
    cout.setf(ios::fixed | ios::showpoint);
    cout.precision(x);
}

ll gcd(ll a, ll b) {
    if (a == 0 || b == 0) return 0;
    while (b) {
        a %= b;
        swap(a, b);
    }
    return a;
}

ll lcm(ll a, ll b) {
    return a / gcd(a, b) * b;
}

ll range_sum(ll a, ll b) {
    if (a > b) return 0ll;
    ll dif = a - 1, cnt = b - a + 1;
    ll ans = ((b - a + 1) * (b - a + 2)) / 2;
    ans += ((b - a + 1) * dif);
    return ans;
}

string dec_to_bin(ll a) {
    string s = "";
    for (ll i = a; i > 0; ) {
        ll k = i % 2;
        i /= 2;
        char c = k + 48;
        s += c;
    }
    if (a == 0) {
        s = "0";
    }
    reverse(all(s));
    return s;
}

ll bin_to_dec(string s) {
    ll num = 0;
    for (int i = 0; i < s.size(); i++) {
        num *= 2ll;
        num += (s[i] - '0');
    }
    return num;
}

ll factorial_by_mod(ll n, ll mod) {
    ll ans = 1;
    ll num;
    for (ll i = 1; i <= n; ++i) {
        num = i % mod;
        ans *= num;
        ans %= mod;
    }
    return ans;
}

bool isPrime(ll a) {
    if (a == 1) return false;
    for (ll i = 2; i * i <= a; i++) {
        if (a % i == 0) return false;
    }
    return true;
}

ll binpow(ll a, ll b) {
    if (!a) return 0;
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans *= a;
        }
        b >>= 1;
        a *= a;
    }
    return ans;
}

ll binpow_by_mod(ll a, ll b, ll mod) {
    if (!a) return 0;
    ll ans = 1;
    while (b) {
        if (b & 1) {
            ans *= a;
            ans %= mod;
        }
        b >>= 1;
        a *= a;
        a %= mod;
    }
    return ans;
}

/* -------------------- Solution -------------------- */

const int N = 100005;
int p[N], from[N], used[N], cyc[N], dep[N], rel[N];
set<int> g[N];
vi cycle;
vector<pii> tree_nodes;
int n, ans, azat;

void dfs_cyc(int u) {
    used[u] = 1;
    int to = p[u];
    if (used[to]) {
        if (to == u) {
            cyc[u] = 1;
            cycle = { u };
            return;
        }
        int node = u;
        while (1) {
            cycle.pub(node);
            cyc[node] = 1;
            if (node == to) break;
            node = from[node];
        }
        return;
    }
    from[to] = u;
    dfs_cyc(to);
}

void dfs_tree(int u) {
    used[u] = 1;
    tree_nodes.pub({ dep[u],u });
    for (auto to : g[u]) {
        if (cyc[to]) continue;
        dep[to] = dep[u] + 1;
        dfs_tree(to);
    }
}

void slv() {
    cin >> n;
    map<string, int> mp;
    int cur = 0;
    for (int i = 1; i <= n; ++i) {
        string x, y;
        cin >> x >> y;
        if (!mp[x]) mp[x] = ++cur;
        if (!mp[y]) mp[y] = ++cur;
        int id1 = mp[x], id2 = mp[y];
        g[id2].insert(id1);
        p[id1] = id2;
    }
    if (n % 2) {
        cout << -1;
        return;
    }
    for (int u = 1; u <= n; ++u) {
        if (used[u]) continue;
        cycle.clear();
        dfs_cyc(u);
        reverse(all(cycle));
        for (auto root : cycle) {
            tree_nodes.clear();
            dfs_tree(root);
            sort(all(tree_nodes));
            while (tree_nodes.size() > 1) {
                int node = tree_nodes.back().ss;
                if (rel[node] || rel[p[node]]) {
                    tree_nodes.pop_back();
                    continue;
                }
                rel[node] = rel[p[node]] = 1;
                ++ans;
                tree_nodes.pop_back();
            }
        }
        int sz = (int)cycle.size();
        if (sz == 1) continue;
        if (sz == 2 && !rel[cycle[0]] && !rel[cycle[1]]) {
            rel[cycle[0]] = rel[cycle[1]] = 1;
        }
        if (sz == 2) continue;
        int ind = 0;
        for (int i = 1; i < sz; ++i) {
            if (rel[cycle[i]]) {
                ind = i;
                break;
            }
        }
        int id = ind + 1;
        if (id == sz) id = 0;
        while (id != ind) {
            int node = cycle[id];
            if (rel[node] || rel[p[node]]) {
                ++id;
                if (id == sz) id = 0;
                continue;
            }
            ++ans;
            rel[node] = rel[p[node]] = 1;
            ++id;
            if (id == sz) id = 0;
            ++id;
            if (id == sz) id = 0;
        }
    }
    for (int u = 1; u <= n; ++u) {
        if (!rel[u]) ++azat;
    }
    cout << ans + azat << '\n';
}

void cs() {
    int tstc = 1;
    //cin >> tstc;
    while (tstc--) {
        slv();
    }
}

void precalc() {
    return;
}

int main() {
    fastio();
    precalc();
    //precision(0);
    cs();
    return 0;
}

• Subtask 1: 0 / 21
• Subtask 2: 25 / 25
• Subtask 3: 29 / 29
• Subtask 4: 0 / 25