oj.uz

Submission #653414

# Submission time Handle Problem Language Result Execution time Memory
653414 2022-10-26T19:01:43 Z pauloamed Network (BOI15_net) C++14
63 / 100
 2000 ms 74648 KB 
#include<bits/stdc++.h>
using namespace std;

const int MAXN = 500010;

struct DSU{
  int sizes[MAXN];
  int parents[MAXN];
  
  DSU(int n){
    for(int i = 0; i < n; ++i){
      sizes[i] = 1;
      parents[i] = i;
    }
  }

  int find(int current){
    int newRoot = current;
    while(newRoot != parents[newRoot]) newRoot = parents[newRoot];

    // rmv if using rollback
    int next;
    while(parents[current] != newRoot){
      next = parents[current];
      parents[current] = newRoot;
    }
    return newRoot;
  }

  void onion(int a, int b){
    a = find(a); b = find(b);
    if(a == b) return;
    if(sizes[a] < sizes[b]) swap(a,b);

    sizes[a] += sizes[b];
    parents[b] = a;
  }
};

vector<int> v[MAXN];
vector<int> u[MAXN];

pair<int,int> deep(int x, int p){
  pair<int,int> ret = {0, x};
  for(auto y : v[x]) if(y != p){
    ret = max(ret, deep(y, x));
  }
  return {ret.first + 1, ret.second};
}

bool mark(int x, int p, int target, DSU &dsu){
  bool has = (x == target);
  for(auto y : v[x]) if(y != p){
    if(mark(y, x, target, dsu)){
      dsu.onion(x, y);
      return true;
    }
  }
  return has;
}

int main(){
  int n; cin >> n;
  for(int i = 0; i + 1 < n; ++i){
    int a, b; cin >> a >> b;
    a--; b--;
    v[a].push_back(b);
    v[b].push_back(a);
  }

  DSU dsu(n);

  vector<pair<int,int>> ans;
  while(dsu.sizes[dsu.find(0)] != n){
    int start = dsu.find(0);
    auto [_, x] = deep(start, -1);
    auto [__, y] = deep(x, -1);

    ans.push_back({x, y});
    mark(x, -1, y, dsu);

    for(int i = 0; i < n; ++i){
      int a = dsu.find(i);
      for(auto y : v[i]){
        int b = dsu.find(y);
        if(a != b){
          u[a].push_back(b);
          u[b].push_back(a);
        }
      }
    }

    for(int i = 0; i < n; ++i) if(dsu.find(i) == i){
      sort(u[i].begin(), u[i].end());
      u[i].erase(unique(u[i].begin(), u[i].end()), u[i].end());
      v[i].clear();
      swap(v[i], u[i]);
    }
  }

  cout << ans.size() << "\n";
  for(auto [a, b] : ans) cout << a + 1 << " " << b + 1 << "\n";

}

Compilation message

net.cpp: In member function 'int DSU::find(int)':
net.cpp:22:9: warning: variable 'next' set but not used [-Wunused-but-set-variable]
   22 |     int next;
      |         ^~~~
net.cpp: In function 'int main()':
net.cpp:76:10: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   76 |     auto [_, x] = deep(start, -1);
      |          ^
net.cpp:77:10: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   77 |     auto [__, y] = deep(x, -1);
      |          ^
net.cpp:102:12: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
  102 |   for(auto [a, b] : ans) cout << a + 1 << " " << b + 1 << "\n";
      |            ^

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 27604 KB Output is correct
2 Correct 15 ms 27604 KB Output is correct
3 Correct 15 ms 27652 KB Output is correct
4 Correct 16 ms 27604 KB Output is correct
5 Correct 16 ms 27748 KB Output is correct
6 Correct 14 ms 27604 KB Output is correct
7 Correct 15 ms 27604 KB Output is correct
8 Correct 18 ms 27664 KB Output is correct
9 Correct 14 ms 27624 KB Output is correct
10 Correct 14 ms 27604 KB Output is correct
11 Correct 14 ms 27604 KB Output is correct
12 Correct 16 ms 27604 KB Output is correct
13 Correct 13 ms 27588 KB Output is correct
14 Correct 15 ms 27696 KB Output is correct
15 Correct 15 ms 27584 KB Output is correct
16 Correct 15 ms 27608 KB Output is correct
17 Correct 14 ms 27604 KB Output is correct
18 Correct 15 ms 27604 KB Output is correct
19 Correct 17 ms 27672 KB Output is correct
20 Correct 14 ms 27608 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 27604 KB Output is correct
2 Correct 15 ms 27604 KB Output is correct
3 Correct 15 ms 27652 KB Output is correct
4 Correct 16 ms 27604 KB Output is correct
5 Correct 16 ms 27748 KB Output is correct
6 Correct 14 ms 27604 KB Output is correct
7 Correct 15 ms 27604 KB Output is correct
8 Correct 18 ms 27664 KB Output is correct
9 Correct 14 ms 27624 KB Output is correct
10 Correct 14 ms 27604 KB Output is correct
11 Correct 14 ms 27604 KB Output is correct
12 Correct 16 ms 27604 KB Output is correct
13 Correct 13 ms 27588 KB Output is correct
14 Correct 15 ms 27696 KB Output is correct
15 Correct 15 ms 27584 KB Output is correct
16 Correct 15 ms 27608 KB Output is correct
17 Correct 14 ms 27604 KB Output is correct
18 Correct 15 ms 27604 KB Output is correct
19 Correct 17 ms 27672 KB Output is correct
20 Correct 14 ms 27608 KB Output is correct
21 Correct 14 ms 27612 KB Output is correct
22 Correct 177 ms 27900 KB Output is correct
23 Correct 174 ms 27980 KB Output is correct
24 Correct 133 ms 27852 KB Output is correct
25 Correct 95 ms 27852 KB Output is correct
26 Correct 70 ms 27852 KB Output is correct
27 Correct 123 ms 27936 KB Output is correct
28 Correct 107 ms 27904 KB Output is correct
29 Correct 73 ms 27860 KB Output is correct
30 Correct 14 ms 27596 KB Output is correct
31 Correct 120 ms 27916 KB Output is correct
32 Correct 16 ms 27604 KB Output is correct
33 Correct 15 ms 27604 KB Output is correct
34 Correct 14 ms 27700 KB Output is correct
35 Correct 14 ms 27604 KB Output is correct
36 Correct 15 ms 27636 KB Output is correct
37 Correct 17 ms 27732 KB Output is correct
38 Correct 15 ms 27748 KB Output is correct
39 Correct 15 ms 27632 KB Output is correct
40 Correct 15 ms 27684 KB Output is correct
41 Correct 15 ms 27684 KB Output is correct
42 Correct 25 ms 27732 KB Output is correct
43 Correct 60 ms 27800 KB Output is correct
44 Correct 16 ms 27604 KB Output is correct
45 Correct 17 ms 27736 KB Output is correct
46 Correct 31 ms 27732 KB Output is correct
47 Correct 16 ms 27700 KB Output is correct
48 Correct 18 ms 27652 KB Output is correct
49 Correct 60 ms 27800 KB Output is correct
50 Correct 14 ms 27604 KB Output is correct
51 Correct 15 ms 27604 KB Output is correct
52 Correct 15 ms 27656 KB Output is correct
53 Correct 22 ms 27792 KB Output is correct
54 Correct 15 ms 27604 KB Output is correct
55 Correct 19 ms 27740 KB Output is correct
56 Correct 15 ms 27604 KB Output is correct
57 Correct 24 ms 27752 KB Output is correct
58 Correct 178 ms 27916 KB Output is correct

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 15 ms 27604 KB Output is correct
2 Correct 15 ms 27604 KB Output is correct
3 Correct 15 ms 27652 KB Output is correct
4 Correct 16 ms 27604 KB Output is correct
5 Correct 16 ms 27748 KB Output is correct
6 Correct 14 ms 27604 KB Output is correct
7 Correct 15 ms 27604 KB Output is correct
8 Correct 18 ms 27664 KB Output is correct
9 Correct 14 ms 27624 KB Output is correct
10 Correct 14 ms 27604 KB Output is correct
11 Correct 14 ms 27604 KB Output is correct
12 Correct 16 ms 27604 KB Output is correct
13 Correct 13 ms 27588 KB Output is correct
14 Correct 15 ms 27696 KB Output is correct
15 Correct 15 ms 27584 KB Output is correct
16 Correct 15 ms 27608 KB Output is correct
17 Correct 14 ms 27604 KB Output is correct
18 Correct 15 ms 27604 KB Output is correct
19 Correct 17 ms 27672 KB Output is correct
20 Correct 14 ms 27608 KB Output is correct
21 Correct 14 ms 27612 KB Output is correct
22 Correct 177 ms 27900 KB Output is correct
23 Correct 174 ms 27980 KB Output is correct
24 Correct 133 ms 27852 KB Output is correct
25 Correct 95 ms 27852 KB Output is correct
26 Correct 70 ms 27852 KB Output is correct
27 Correct 123 ms 27936 KB Output is correct
28 Correct 107 ms 27904 KB Output is correct
29 Correct 73 ms 27860 KB Output is correct
30 Correct 14 ms 27596 KB Output is correct
31 Correct 120 ms 27916 KB Output is correct
32 Correct 16 ms 27604 KB Output is correct
33 Correct 15 ms 27604 KB Output is correct
34 Correct 14 ms 27700 KB Output is correct
35 Correct 14 ms 27604 KB Output is correct
36 Correct 15 ms 27636 KB Output is correct
37 Correct 17 ms 27732 KB Output is correct
38 Correct 15 ms 27748 KB Output is correct
39 Correct 15 ms 27632 KB Output is correct
40 Correct 15 ms 27684 KB Output is correct
41 Correct 15 ms 27684 KB Output is correct
42 Correct 25 ms 27732 KB Output is correct
43 Correct 60 ms 27800 KB Output is correct
44 Correct 16 ms 27604 KB Output is correct
45 Correct 17 ms 27736 KB Output is correct
46 Correct 31 ms 27732 KB Output is correct
47 Correct 16 ms 27700 KB Output is correct
48 Correct 18 ms 27652 KB Output is correct
49 Correct 60 ms 27800 KB Output is correct
50 Correct 14 ms 27604 KB Output is correct
51 Correct 15 ms 27604 KB Output is correct
52 Correct 15 ms 27656 KB Output is correct
53 Correct 22 ms 27792 KB Output is correct
54 Correct 15 ms 27604 KB Output is correct
55 Correct 19 ms 27740 KB Output is correct
56 Correct 15 ms 27604 KB Output is correct
57 Correct 24 ms 27752 KB Output is correct
58 Correct 178 ms 27916 KB Output is correct
59 Execution timed out 2061 ms 74648 KB Time limit exceeded
60 Halted 0 ms 0 KB -