oj.uz

Submission #702251

# Submission time Handle Problem Language Result Execution time Memory
702251 2023-02-23T11:36:13 Z Shreyan_Paliwal Love Polygon (BOI18_polygon) C++17
75 / 100
 409 ms 25228 KB 
// #include <iostream>
// #include <vector>
// #include <map>
// using namespace std;

// const int maxn = 1e5 + 5;

// int n;
// int par[maxn];

// int vis[maxn];
// vector<int> cycle_starts;

// vector<int> adj[maxn];

// bool dfs_find_cycle(int nd) {
//     vis[nd] = 1; // current vertex visited

//     if (vis[par[nd]] == 0) { // if next vertex unvisited dfs_find_cycle into it
//         if (dfs_find_cycle(par[nd])) {
//             vis[nd] = 2;
//             return true;
//         }
//     } else if (vis[par[nd]] == 1) { // if visited next vertex in current iteration
//         cycle_starts.push_back(nd);
//         vis[nd] = 2;
//         return true; // back out
//     }

//     vis[nd] = 2; // mark current vertex visited
//     return false;
// }

// void find_components() {
//     for (int i = 0; i < n; i++) {
//         if (vis[i]) continue;
//         dfs_find_cycle(i);
//     }
// }

// void read_input() {
//     cin >> n;
    
//     map<string, int> m;
//     int cnt = 0;
//     for (int i = 0; i < n; i++) {
//         string a, b; cin >> a >> b;
//         // if (m.find(a) == m.end()) cout << a << ' ' << cnt << endl;
//         if (m.find(a) == m.end())
//             m[a] = cnt++;
//         // if (m.find(b) == m.end()) cout << b << ' ' << cnt << endl;
//         if (m.find(b) == m.end())
//             m[b] = cnt++;
//         par[m[a]] = m[b];

//         adj[m[a]].push_back(m[b]);
//         adj[m[b]].push_back(m[a]);
//     }
// }

// int cur_root = -1;

// int F[maxn], G[maxn];
// int f(int x, int par); int g(int x, int par);
// int f(int x, int par) {
//     F[x] = 1;
//     for (auto i : adj[x])
//         if (i != par && i != cur_root)
//             F[x] += g(i, x);
//     // cout << "f " << x << ' ' << F[x] << endl;
//     return F[x];
// }
// int g(int x, int par) {
//     G[x] = f(x, par) - 1;
//     int max_fg = 0;
//     for (auto i : adj[x])
//         if (i != par && i != cur_root)
//             max_fg = max(max_fg, f(i, x) - g(i, x));
//     G[x] += max_fg;
//     // cout << "g " << x << ' ' << G[x] << endl;
//     return G[x];
// }

// int main() {
//     // freopen("main.in", "r", stdin);

//     read_input();

//     if (n & 1) { cout << -1 << endl; return 0; }

//     find_components();

//     fill(F, F + maxn, -1);
//     fill(G, G + maxn, -1);
//     int sum_root_g = 0;
//     for (auto i : cycle_starts) {
//         // cycle starts @ i & size 1
//         if (i == par[i]) {
//             cur_root = i;
//             sum_root_g += g(i, i);
//         }

//         // size 2
//         else if (i == par[par[i]]) {
//             // cout << sum_root_g << ' ';
//             // optimal to take arc
//             // i, par[i]
//             for (auto j : adj[i])
//                 if (j != par[i])
//                     sum_root_g += g(j, i);
//             for (auto j : adj[par[i]])
//                 if (j != i)
//                     sum_root_g += g(j, par[j]);
//             sum_root_g += 2;
//             // cout << sum_root_g << endl;
//         }

//         else {
//             // cout << i << endl;
//             // par[i] --> ... --> i --> par[i]
//             cur_root = par[i];

//             // take arc
//             int with_arc = 1;
//             for (auto j : adj[i])
//                 if (j != par[i])
//                     with_arc += g(j, i);
//             for (auto j : adj[par[i]])
//                 if (j != i)
//                     with_arc += g(j, par[i]);
//             // cout << "with arc " << i << ' ' << par[i] << ' ' << with_arc << endl;

        
//             int without_arc = g(par[i], i);
//             // cout << "without arc " << i << ' ' << par[i] << ' ' << without_arc << endl;

//             sum_root_g += max(with_arc, without_arc);
//         }
//     }

//     cout << n - sum_root_g << endl;

//     return 0;
// }

// #include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <map>
using namespace std;


const int maxn = 1e5 + 5;

int n;
int par[maxn];
vector<int> adj[maxn];

int vis[maxn];
vector<int> cyc_starts;

void read_input() {
    cin >> n; int cnt = 0;
    map<string, int> m;
    for (int i = 0; i < n; i++) {
        string a, b; cin >> a >> b;
        if (m.find(a) == m.end()) m[a] = cnt++;
        if (m.find(b) == m.end()) m[b] = cnt++;

        par[m[a]] = m[b];

        adj[m[a]].push_back(m[b]);
        adj[m[b]].push_back(m[a]);
    }
}

bool dfs(int nd) {
    vis[nd] = 1;

    if (vis[par[nd]] == 2) {vis[nd] = 2; return false;}
    if (vis[par[nd]] == 1) {
        cyc_starts.push_back(nd);
        vis[nd] = 2;
        return true;
    }

    bool ret = dfs(par[nd]);
    vis[nd] = 2;
    return ret;
}

void find_cycs() {
    for (int i = 0; i < n; i++) {
        if (vis[i]) continue;
        dfs(i);
    }
}

int cur_root = -1;

int F[maxn], G[maxn];
void rec_fg(int nd, int par) {
    F[nd] = 1, G[nd] = 0;
    for (auto i : adj[nd])
        if (i != par && i != cur_root) {
            // recurse 
            rec_fg(i, nd);
            F[nd] += G[i];
            G[nd] = max(G[nd], F[i] - G[i]);
        }
    G[nd] += F[nd] - 1;
    // cout << nd << ' ' << F[nd] << ' ' << G[nd] << endl;
}

int main() {
    // freopen("main.in", "r", stdin);

    read_input(); if (n & 1) { cout << -1 << endl; return 0; }
    find_cycs();

    int sum_s = 0;
    for (auto i : cyc_starts) {
        // cout << "---------------" << endl;
        // cout << i << endl;
        // if cycle size is 1
        if (i == par[i]) {
            cur_root = i;
            rec_fg(i, i);
            sum_s += G[i];
        } else if (i == par[par[i]]) {
            // children if i
            cur_root = -1;
            // cout << sum_s << endl;
            rec_fg(i, par[i]);
            for (auto j : adj[i])
                if (j != par[i])
                    sum_s += G[j];
            rec_fg(par[i], i);
            for (auto j : adj[par[i]])
                if (j != i)
                    sum_s += G[j];
            sum_s += 2;
            // cout << sum_s << endl;
        } else {
            // without arc i -- par[i]
            cur_root = par[i];
            rec_fg(par[i], i);
            int without_arc = G[par[i]];

            // with arc i -- par[i]
            int with_arc = 1;
            cur_root = i;
            rec_fg(par[i], i);
            for (auto j : adj[par[i]])
                if (j != i)
                    with_arc += G[j];
            // cout << "next" << endl;
            cur_root = par[i];
            rec_fg(i, par[i]);
            for (auto j : adj[i])
                if (j != par[i] && par[j] != i)
                    with_arc += G[j];
            // cout << without_arc << ' ' << with_arc << endl;
            sum_s += max(without_arc, with_arc);
        }
    }

    cout << n - sum_s << endl;
    return 0;
}

Subtask #1
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2660 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 1 ms 2660 KB Output is correct
4 Correct 2 ms 2772 KB Output is correct
5 Correct 1 ms 2660 KB Output is correct
6 Correct 3 ms 2644 KB Output is correct
7 Correct 1 ms 2644 KB Output is correct
8 Correct 2 ms 2660 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 1 ms 2644 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 2 ms 2664 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 2 ms 2660 KB Output is correct
15 Correct 2 ms 2660 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2664 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2656 KB Output is correct
4 Correct 399 ms 24012 KB Output is correct
5 Correct 367 ms 17412 KB Output is correct
6 Correct 409 ms 25228 KB Output is correct
7 Correct 343 ms 16076 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 375 ms 17292 KB Output is correct
2 Correct 346 ms 19024 KB Output is correct
3 Correct 289 ms 17816 KB Output is correct
4 Correct 329 ms 16188 KB Output is correct
5 Correct 386 ms 24512 KB Output is correct
6 Correct 342 ms 17300 KB Output is correct
7 Correct 385 ms 17424 KB Output is correct
8 Correct 362 ms 17644 KB Output is correct
9 Correct 322 ms 17504 KB Output is correct
10 Correct 284 ms 17624 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 2 ms 2644 KB Output is correct
13 Correct 1 ms 2664 KB Output is correct
14 Correct 1 ms 2656 KB Output is correct

Subtask #4
0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2660 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 1 ms 2660 KB Output is correct
4 Correct 2 ms 2772 KB Output is correct
5 Correct 1 ms 2660 KB Output is correct
6 Correct 3 ms 2644 KB Output is correct
7 Correct 1 ms 2644 KB Output is correct
8 Correct 2 ms 2660 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 1 ms 2644 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 2 ms 2664 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 2 ms 2660 KB Output is correct
15 Correct 2 ms 2660 KB Output is correct
16 Correct 1 ms 2664 KB Output is correct
17 Correct 2 ms 2644 KB Output is correct
18 Correct 2 ms 2656 KB Output is correct
19 Correct 399 ms 24012 KB Output is correct
20 Correct 367 ms 17412 KB Output is correct
21 Correct 409 ms 25228 KB Output is correct
22 Correct 343 ms 16076 KB Output is correct
23 Correct 375 ms 17292 KB Output is correct
24 Correct 346 ms 19024 KB Output is correct
25 Correct 289 ms 17816 KB Output is correct
26 Correct 329 ms 16188 KB Output is correct
27 Correct 386 ms 24512 KB Output is correct
28 Correct 342 ms 17300 KB Output is correct
29 Correct 385 ms 17424 KB Output is correct
30 Correct 362 ms 17644 KB Output is correct
31 Correct 322 ms 17504 KB Output is correct
32 Correct 284 ms 17624 KB Output is correct
33 Correct 2 ms 2644 KB Output is correct
34 Correct 2 ms 2644 KB Output is correct
35 Correct 1 ms 2664 KB Output is correct
36 Correct 1 ms 2656 KB Output is correct
37 Correct 396 ms 17296 KB Output is correct
38 Incorrect 380 ms 18668 KB Output isn't correct
39 Halted 0 ms 0 KB -