oj.uz

Submission #653413

# Submission time Handle Problem Language Result Execution time Memory
653413 2022-10-26T19:01:02 Z pauloamed Network (BOI15_net) C++14
63 / 100
 193 ms 22740 KB 
#include<bits/stdc++.h>
using namespace std;

const int MAXN = 200000;

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 6 ms 11220 KB Output is correct
2 Correct 6 ms 11220 KB Output is correct
3 Correct 7 ms 11220 KB Output is correct
4 Correct 6 ms 11220 KB Output is correct
5 Correct 7 ms 11220 KB Output is correct
6 Correct 6 ms 11236 KB Output is correct
7 Correct 6 ms 11220 KB Output is correct
8 Correct 7 ms 11256 KB Output is correct
9 Correct 6 ms 11220 KB Output is correct
10 Correct 7 ms 11220 KB Output is correct
11 Correct 7 ms 11220 KB Output is correct
12 Correct 7 ms 11252 KB Output is correct
13 Correct 6 ms 11220 KB Output is correct
14 Correct 6 ms 11220 KB Output is correct
15 Correct 6 ms 11220 KB Output is correct
16 Correct 6 ms 11220 KB Output is correct
17 Correct 6 ms 11220 KB Output is correct
18 Correct 7 ms 11252 KB Output is correct
19 Correct 7 ms 11184 KB Output is correct
20 Correct 7 ms 11164 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11220 KB Output is correct
2 Correct 6 ms 11220 KB Output is correct
3 Correct 7 ms 11220 KB Output is correct
4 Correct 6 ms 11220 KB Output is correct
5 Correct 7 ms 11220 KB Output is correct
6 Correct 6 ms 11236 KB Output is correct
7 Correct 6 ms 11220 KB Output is correct
8 Correct 7 ms 11256 KB Output is correct
9 Correct 6 ms 11220 KB Output is correct
10 Correct 7 ms 11220 KB Output is correct
11 Correct 7 ms 11220 KB Output is correct
12 Correct 7 ms 11252 KB Output is correct
13 Correct 6 ms 11220 KB Output is correct
14 Correct 6 ms 11220 KB Output is correct
15 Correct 6 ms 11220 KB Output is correct
16 Correct 6 ms 11220 KB Output is correct
17 Correct 6 ms 11220 KB Output is correct
18 Correct 7 ms 11252 KB Output is correct
19 Correct 7 ms 11184 KB Output is correct
20 Correct 7 ms 11164 KB Output is correct
21 Correct 7 ms 11220 KB Output is correct
22 Correct 170 ms 11480 KB Output is correct
23 Correct 184 ms 11496 KB Output is correct
24 Correct 130 ms 11552 KB Output is correct
25 Correct 84 ms 11420 KB Output is correct
26 Correct 64 ms 11420 KB Output is correct
27 Correct 118 ms 11508 KB Output is correct
28 Correct 101 ms 11604 KB Output is correct
29 Correct 63 ms 11348 KB Output is correct
30 Correct 8 ms 11220 KB Output is correct
31 Correct 126 ms 11488 KB Output is correct
32 Correct 6 ms 11260 KB Output is correct
33 Correct 7 ms 11220 KB Output is correct
34 Correct 6 ms 11220 KB Output is correct
35 Correct 7 ms 11260 KB Output is correct
36 Correct 6 ms 11260 KB Output is correct
37 Correct 7 ms 11260 KB Output is correct
38 Correct 7 ms 11348 KB Output is correct
39 Correct 7 ms 11256 KB Output is correct
40 Correct 6 ms 11220 KB Output is correct
41 Correct 7 ms 11248 KB Output is correct
42 Correct 17 ms 11316 KB Output is correct
43 Correct 52 ms 11356 KB Output is correct
44 Correct 6 ms 11220 KB Output is correct
45 Correct 9 ms 11220 KB Output is correct
46 Correct 24 ms 11292 KB Output is correct
47 Correct 6 ms 11220 KB Output is correct
48 Correct 10 ms 11224 KB Output is correct
49 Correct 57 ms 11348 KB Output is correct
50 Correct 7 ms 11220 KB Output is correct
51 Correct 6 ms 11256 KB Output is correct
52 Correct 8 ms 11220 KB Output is correct
53 Correct 14 ms 11348 KB Output is correct
54 Correct 6 ms 11256 KB Output is correct
55 Correct 11 ms 11220 KB Output is correct
56 Correct 7 ms 11220 KB Output is correct
57 Correct 16 ms 11220 KB Output is correct
58 Correct 193 ms 11504 KB Output is correct

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11220 KB Output is correct
2 Correct 6 ms 11220 KB Output is correct
3 Correct 7 ms 11220 KB Output is correct
4 Correct 6 ms 11220 KB Output is correct
5 Correct 7 ms 11220 KB Output is correct
6 Correct 6 ms 11236 KB Output is correct
7 Correct 6 ms 11220 KB Output is correct
8 Correct 7 ms 11256 KB Output is correct
9 Correct 6 ms 11220 KB Output is correct
10 Correct 7 ms 11220 KB Output is correct
11 Correct 7 ms 11220 KB Output is correct
12 Correct 7 ms 11252 KB Output is correct
13 Correct 6 ms 11220 KB Output is correct
14 Correct 6 ms 11220 KB Output is correct
15 Correct 6 ms 11220 KB Output is correct
16 Correct 6 ms 11220 KB Output is correct
17 Correct 6 ms 11220 KB Output is correct
18 Correct 7 ms 11252 KB Output is correct
19 Correct 7 ms 11184 KB Output is correct
20 Correct 7 ms 11164 KB Output is correct
21 Correct 7 ms 11220 KB Output is correct
22 Correct 170 ms 11480 KB Output is correct
23 Correct 184 ms 11496 KB Output is correct
24 Correct 130 ms 11552 KB Output is correct
25 Correct 84 ms 11420 KB Output is correct
26 Correct 64 ms 11420 KB Output is correct
27 Correct 118 ms 11508 KB Output is correct
28 Correct 101 ms 11604 KB Output is correct
29 Correct 63 ms 11348 KB Output is correct
30 Correct 8 ms 11220 KB Output is correct
31 Correct 126 ms 11488 KB Output is correct
32 Correct 6 ms 11260 KB Output is correct
33 Correct 7 ms 11220 KB Output is correct
34 Correct 6 ms 11220 KB Output is correct
35 Correct 7 ms 11260 KB Output is correct
36 Correct 6 ms 11260 KB Output is correct
37 Correct 7 ms 11260 KB Output is correct
38 Correct 7 ms 11348 KB Output is correct
39 Correct 7 ms 11256 KB Output is correct
40 Correct 6 ms 11220 KB Output is correct
41 Correct 7 ms 11248 KB Output is correct
42 Correct 17 ms 11316 KB Output is correct
43 Correct 52 ms 11356 KB Output is correct
44 Correct 6 ms 11220 KB Output is correct
45 Correct 9 ms 11220 KB Output is correct
46 Correct 24 ms 11292 KB Output is correct
47 Correct 6 ms 11220 KB Output is correct
48 Correct 10 ms 11224 KB Output is correct
49 Correct 57 ms 11348 KB Output is correct
50 Correct 7 ms 11220 KB Output is correct
51 Correct 6 ms 11256 KB Output is correct
52 Correct 8 ms 11220 KB Output is correct
53 Correct 14 ms 11348 KB Output is correct
54 Correct 6 ms 11256 KB Output is correct
55 Correct 11 ms 11220 KB Output is correct
56 Correct 7 ms 11220 KB Output is correct
57 Correct 16 ms 11220 KB Output is correct
58 Correct 193 ms 11504 KB Output is correct
59 Runtime error 15 ms 22740 KB Execution killed with signal 11
60 Halted 0 ms 0 KB -