oj.uz

Submission #717502

# Submission time Handle Problem Language Result Execution time Memory
717502 2023-04-02T03:03:43 Z Charizard2021 Network (BOI15_net) C++17
18 / 100
 22 ms 35796 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 20 ms 35540 KB Output is correct
2 Correct 21 ms 35560 KB Output is correct
3 Correct 18 ms 35560 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 35520 KB Output is correct
7 Correct 18 ms 35540 KB Output is correct
8 Correct 18 ms 35540 KB Output is correct
9 Correct 19 ms 35540 KB Output is correct
10 Correct 20 ms 35472 KB Output is correct
11 Correct 19 ms 35540 KB Output is correct
12 Correct 19 ms 35668 KB Output is correct
13 Correct 18 ms 35536 KB Output is correct
14 Correct 18 ms 35556 KB Output is correct
15 Correct 18 ms 35560 KB Output is correct
16 Correct 18 ms 35464 KB Output is correct
17 Correct 18 ms 35540 KB Output is correct
18 Correct 22 ms 35532 KB Output is correct
19 Correct 20 ms 35560 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 20 ms 35540 KB Output is correct
2 Correct 21 ms 35560 KB Output is correct
3 Correct 18 ms 35560 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 35520 KB Output is correct
7 Correct 18 ms 35540 KB Output is correct
8 Correct 18 ms 35540 KB Output is correct
9 Correct 19 ms 35540 KB Output is correct
10 Correct 20 ms 35472 KB Output is correct
11 Correct 19 ms 35540 KB Output is correct
12 Correct 19 ms 35668 KB Output is correct
13 Correct 18 ms 35536 KB Output is correct
14 Correct 18 ms 35556 KB Output is correct
15 Correct 18 ms 35560 KB Output is correct
16 Correct 18 ms 35464 KB Output is correct
17 Correct 18 ms 35540 KB Output is correct
18 Correct 22 ms 35532 KB Output is correct
19 Correct 20 ms 35560 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct
21 Correct 20 ms 35564 KB Output is correct
22 Correct 20 ms 35796 KB Output is correct
23 Correct 21 ms 35792 KB Output is correct
24 Correct 19 ms 35796 KB Output is correct
25 Correct 20 ms 35660 KB Output is correct
26 Correct 19 ms 35688 KB Output is correct
27 Incorrect 19 ms 35668 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 20 ms 35540 KB Output is correct
2 Correct 21 ms 35560 KB Output is correct
3 Correct 18 ms 35560 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 35520 KB Output is correct
7 Correct 18 ms 35540 KB Output is correct
8 Correct 18 ms 35540 KB Output is correct
9 Correct 19 ms 35540 KB Output is correct
10 Correct 20 ms 35472 KB Output is correct
11 Correct 19 ms 35540 KB Output is correct
12 Correct 19 ms 35668 KB Output is correct
13 Correct 18 ms 35536 KB Output is correct
14 Correct 18 ms 35556 KB Output is correct
15 Correct 18 ms 35560 KB Output is correct
16 Correct 18 ms 35464 KB Output is correct
17 Correct 18 ms 35540 KB Output is correct
18 Correct 22 ms 35532 KB Output is correct
19 Correct 20 ms 35560 KB Output is correct
20 Correct 18 ms 35540 KB Output is correct
21 Correct 20 ms 35564 KB Output is correct
22 Correct 20 ms 35796 KB Output is correct
23 Correct 21 ms 35792 KB Output is correct
24 Correct 19 ms 35796 KB Output is correct
25 Correct 20 ms 35660 KB Output is correct
26 Correct 19 ms 35688 KB Output is correct
27 Incorrect 19 ms 35668 KB Breaking single line is causing network to disconnect.
28 Halted 0 ms 0 KB -