oj.uz

Submission #717507

# Submission time Handle Problem Language Result Execution time Memory
717507 2023-04-02T03:09:36 Z Charizard2021 Network (BOI15_net) C++17
18 / 100
 22 ms 35836 KB 
#include<bits/stdc++.h>
using namespace std;
const int N = 500001;
#define IOS ios::sync_with_stdio(false);; cin.tie(NULL)
bool visited[N];
int LeavesInsubtee[N];
vector<int> adj[N];
vector<int> res[N];
vector<int> v2[N];
int n;
int ans = 0;
int cur_ans = 0;
int subtreeValue = 0;
void dfs(int u){
    visited[u] = true;
    if((int)adj[u].size() == 1){
        LeavesInsubtee[u] = 1;
    }
    for(int v : adj[u]){
        if(!visited[v]){
            dfs(v);
            LeavesInsubtee[u] += LeavesInsubtee[v];
        }
    }
}
void dfs2(int u){
    visited[u] = true;
    if((int)adj[u].size() == 1){
        res[subtreeValue].push_back(u);
    }
    for(int v : adj[u]){
        if(!visited[v]){
            dfs2(v);
        }
    }
}
int cutlocation(int u){
    visited[u] = true;
    for(int v : adj[u]){
        if(!visited[v]){
            if(LeavesInsubtee[v] > floor((cur_ans)/2)){
                return cutlocation(v);
            }
        }
    }
    return u;
}
int cut(int u){
    dfs(1);
    for(int i = 1; i <= n; i++){
        visited[i] = false;
    }
    int x = cutlocation(1);
    for(int i = 1; i <= n; i++){
        visited[i] = false;
    }
    visited[x] = true;
    for(int v : adj[x]){
        subtreeValue++;
        dfs2(v);
    }
    return x;
}
struct cmp{
    bool operator()(const int &a, const int &b) const{
        if(res[a].size() == res[b].size()){
            return a < b;
        }
        return res[a].size() > res[b].size();
    }
};
int main(){
    IOS;
    cin >> n;
    for(int i = 0; i < n - 1; i++){
        int a, b;
        cin >> a >> b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    for(int i = 1; i <= n; i++){
        if((int)adj[i].size() == 1){
            ans++;
        }
    }
    cur_ans = ans;
    ans = (ans + 1)/2;
    cout << ans << "\n";
    cut(n);
    vector<int> v;
    vector<int> res2[subtreeValue + 1];
    for(int i = 1; i <= subtreeValue; i++){
        v2[res[i].size()].push_back(i);
        res2[i] = res[i];
    }
    int first_pointer = -1;
    int second_pointer = -1;
    for(int i = N - 1; i > 0; i--){
        if(!v2[i].empty() && first_pointer == -1){
            first_pointer = i;
        }
        if(v2[i].size() > 1 && second_pointer == -1){
            second_pointer = i;
        }
    }
    while(first_pointer != 0){
        int x = v2[first_pointer].back();
        v.push_back(res[x].back());
        v2[first_pointer].pop_back();
        res[x].pop_back();
        if(second_pointer > 0 && v2[second_pointer].size() != 0){
            int y = v2[second_pointer].back();
            v.push_back(res[y].back());
            v2[second_pointer].pop_back();
            res[y].pop_back();
            if(!res[y].empty()){
                v2[res[y].size()].push_back(y);
            }
            if((first_pointer == second_pointer && v2[res[y].size() + 1].size() <= 1) || (first_pointer != second_pointer && v2[res[y].size() + 1].size() == 0)){
                second_pointer--;
            }
        }
        if(!res[x].empty()){
            v2[res[x].size()].push_back(x);
        }
        if(v2[res[x].size() + 1].size() == 0){
            first_pointer--;
        }
    }
    if(v.size() % 2 == 1){
        for(int i = 1; i <= subtreeValue; i++){
            for(int j = 0; j < res2[i].size(); j++){
                if(res2[i][j] != v.back()){
                    v.push_back(res2[i][j]);
                    break;
                }
            }
            if(v.size() % 2== 0){
                break;
            }
        }
    }
    for(int i = 0; i < (int)v.size(); i += 2){
        cout << v[i] << " " << v[i + 1] << "\n";
    }
}

Compilation message

net.cpp: In function 'int main()':
net.cpp:132:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  132 |             for(int j = 0; j < res2[i].size(); j++){
      |                            ~~^~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 35540 KB Output is correct
2 Correct 18 ms 35508 KB Output is correct
3 Correct 18 ms 35540 KB Output is correct
4 Correct 18 ms 35540 KB Output is correct
5 Correct 18 ms 35540 KB Output is correct
6 Correct 18 ms 35472 KB Output is correct
7 Correct 18 ms 35564 KB Output is correct
8 Correct 18 ms 35560 KB Output is correct
9 Correct 18 ms 35540 KB Output is correct
10 Correct 21 ms 35728 KB Output is correct
11 Correct 22 ms 35496 KB Output is correct
12 Correct 20 ms 35540 KB Output is correct
13 Correct 19 ms 35564 KB Output is correct
14 Correct 19 ms 35460 KB Output is correct
15 Correct 17 ms 35540 KB Output is correct
16 Correct 19 ms 35560 KB Output is correct
17 Correct 20 ms 35556 KB Output is correct
18 Correct 20 ms 35540 KB Output is correct
19 Correct 19 ms 35472 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 35540 KB Output is correct
2 Correct 18 ms 35508 KB Output is correct
3 Correct 18 ms 35540 KB Output is correct
4 Correct 18 ms 35540 KB Output is correct
5 Correct 18 ms 35540 KB Output is correct
6 Correct 18 ms 35472 KB Output is correct
7 Correct 18 ms 35564 KB Output is correct
8 Correct 18 ms 35560 KB Output is correct
9 Correct 18 ms 35540 KB Output is correct
10 Correct 21 ms 35728 KB Output is correct
11 Correct 22 ms 35496 KB Output is correct
12 Correct 20 ms 35540 KB Output is correct
13 Correct 19 ms 35564 KB Output is correct
14 Correct 19 ms 35460 KB Output is correct
15 Correct 17 ms 35540 KB Output is correct
16 Correct 19 ms 35560 KB Output is correct
17 Correct 20 ms 35556 KB Output is correct
18 Correct 20 ms 35540 KB Output is correct
19 Correct 19 ms 35472 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct
21 Correct 18 ms 35540 KB Output is correct
22 Correct 19 ms 35720 KB Output is correct
23 Correct 20 ms 35688 KB Output is correct
24 Correct 20 ms 35836 KB Output is correct
25 Correct 19 ms 35796 KB Output is correct
26 Correct 18 ms 35700 KB Output is correct
27 Incorrect 18 ms 35564 KB Breaking single line is causing network to disconnect.
28 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 19 ms 35540 KB Output is correct
2 Correct 18 ms 35508 KB Output is correct
3 Correct 18 ms 35540 KB Output is correct
4 Correct 18 ms 35540 KB Output is correct
5 Correct 18 ms 35540 KB Output is correct
6 Correct 18 ms 35472 KB Output is correct
7 Correct 18 ms 35564 KB Output is correct
8 Correct 18 ms 35560 KB Output is correct
9 Correct 18 ms 35540 KB Output is correct
10 Correct 21 ms 35728 KB Output is correct
11 Correct 22 ms 35496 KB Output is correct
12 Correct 20 ms 35540 KB Output is correct
13 Correct 19 ms 35564 KB Output is correct
14 Correct 19 ms 35460 KB Output is correct
15 Correct 17 ms 35540 KB Output is correct
16 Correct 19 ms 35560 KB Output is correct
17 Correct 20 ms 35556 KB Output is correct
18 Correct 20 ms 35540 KB Output is correct
19 Correct 19 ms 35472 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct
21 Correct 18 ms 35540 KB Output is correct
22 Correct 19 ms 35720 KB Output is correct
23 Correct 20 ms 35688 KB Output is correct
24 Correct 20 ms 35836 KB Output is correct
25 Correct 19 ms 35796 KB Output is correct
26 Correct 18 ms 35700 KB Output is correct
27 Incorrect 18 ms 35564 KB Breaking single line is causing network to disconnect.
28 Halted 0 ms 0 KB -