# |
Submission time |
Handle |
Problem |
Language |
Result |
Execution time |
Memory |
931643 |
2024-02-22T07:40:48 Z |
vjudge1 |
Network (BOI15_net) |
C++17 |
|
2000 ms |
75192 KB |
#include<bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
#define pb push_back
#define F first
#define S second
#define len(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define file freopen("matrix.txt", "r", stdin);freopen("a.out", "w", stdout);
#define kill(x) {cout << x << '\n'; continue;}
//#define int long long
const int maxn = 500'000 + 5, LG = 20, MOD = 1e9+7;// 998244353
const ll inf = 1061109567;
//priority_queue< pii , vector<pii> , greater<pii> pq;
int n, d[maxn], par[LG][maxn];
vector<int> g[maxn];
bitset<maxn> mark;
void dfs(int v = 1, int p = 0) {
for(int i = 1; i < LG; ++i)
par[i][v] = par[i-1][par[i-1][v]];
for(int u : g[v])
if(u ^ p) {
par[0][u] = v;
d[u] = d[v] + 1;
dfs(u, v);
}
}
int lca(int v, int u) {
if(v == u) return v;
if(d[v] < d[u]) swap(u, v);
int distance = d[v] - d[u];
for(int i = 0; i < LG; ++i)
if(distance & (1 << i)) v = par[i][v];
if(u == v) return v;
while(u != v) {
int l = 0, r = LG;
while(r-l > 1) {
int mid = (r+l) / 2;
if(par[mid][u] == par[mid][v]) r = mid;
else l = mid;
}
u = par[l][u], v = par[l][v];
}
return v;
}
signed main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n;
for(int i = 0; i < n-1; ++i) {
int v, u;
cin >> v >> u;
g[v].pb(u); g[u].pb(v);
}
dfs();
vector<int> l;
for(int i = 1; i <= n; ++i) if(len(g[i]) == 1) l.pb(i);
int leaves = len(l);
vector<pair<int, pii>> v;
for(int i = 0; i < leaves; ++i) {
for(int j = i+1; j < leaves; ++j) {
int LCA = lca(l[i], l[j]);
v.pb({d[l[i]] + d[l[j]] - 2 * d[LCA], {l[i], l[j]}});
}
}
sort(all(v));
reverse(all(v));
cout << (leaves + 1)/2 << '\n';
for(int i = 0; i < len(v); ++i) {
int vv = v[i].S.F, u = v[i].S.S;
if(mark.count() == leaves) break;
if(!mark[vv] && !mark[u]) {
cout << vv << ' ' << u << '\n';
mark[vv] = mark[u] = 1;
}
else {
if(leaves % 2 == 0) continue;
else
if(mark.count() == leaves - 1) {
if(!mark[vv]) {
cout << vv << ' ' << v[0].S.F << '\n';
break;
}
else if(!mark[u]){
cout << u << ' ' << v[0].S.F << '\n';
break;
}
}
}
}
}
Compilation message
net.cpp: In function 'int main()':
net.cpp:96:19: warning: comparison of integer expressions of different signedness: 'std::size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
96 | if(mark.count() == leaves) break;
| ~~~~~~~~~~~~~^~~~~~~~~
net.cpp:104:21: warning: comparison of integer expressions of different signedness: 'std::size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
104 | if(mark.count() == leaves - 1) {
| ~~~~~~~~~~~~~^~~~~~~~~~~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
11 ms |
49756 KB |
Output is correct |
2 |
Correct |
7 ms |
49780 KB |
Output is correct |
3 |
Correct |
8 ms |
49756 KB |
Output is correct |
4 |
Correct |
7 ms |
49756 KB |
Output is correct |
5 |
Correct |
7 ms |
49752 KB |
Output is correct |
6 |
Correct |
7 ms |
49756 KB |
Output is correct |
7 |
Correct |
7 ms |
49756 KB |
Output is correct |
8 |
Correct |
7 ms |
49756 KB |
Output is correct |
9 |
Correct |
7 ms |
49752 KB |
Output is correct |
10 |
Correct |
7 ms |
49756 KB |
Output is correct |
11 |
Correct |
7 ms |
49756 KB |
Output is correct |
12 |
Correct |
7 ms |
49760 KB |
Output is correct |
13 |
Correct |
7 ms |
49756 KB |
Output is correct |
14 |
Correct |
7 ms |
49752 KB |
Output is correct |
15 |
Correct |
7 ms |
49756 KB |
Output is correct |
16 |
Correct |
7 ms |
49696 KB |
Output is correct |
17 |
Correct |
7 ms |
49756 KB |
Output is correct |
18 |
Correct |
8 ms |
49756 KB |
Output is correct |
19 |
Correct |
8 ms |
49708 KB |
Output is correct |
20 |
Correct |
7 ms |
49756 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
11 ms |
49756 KB |
Output is correct |
2 |
Correct |
7 ms |
49780 KB |
Output is correct |
3 |
Correct |
8 ms |
49756 KB |
Output is correct |
4 |
Correct |
7 ms |
49756 KB |
Output is correct |
5 |
Correct |
7 ms |
49752 KB |
Output is correct |
6 |
Correct |
7 ms |
49756 KB |
Output is correct |
7 |
Correct |
7 ms |
49756 KB |
Output is correct |
8 |
Correct |
7 ms |
49756 KB |
Output is correct |
9 |
Correct |
7 ms |
49752 KB |
Output is correct |
10 |
Correct |
7 ms |
49756 KB |
Output is correct |
11 |
Correct |
7 ms |
49756 KB |
Output is correct |
12 |
Correct |
7 ms |
49760 KB |
Output is correct |
13 |
Correct |
7 ms |
49756 KB |
Output is correct |
14 |
Correct |
7 ms |
49752 KB |
Output is correct |
15 |
Correct |
7 ms |
49756 KB |
Output is correct |
16 |
Correct |
7 ms |
49696 KB |
Output is correct |
17 |
Correct |
7 ms |
49756 KB |
Output is correct |
18 |
Correct |
8 ms |
49756 KB |
Output is correct |
19 |
Correct |
8 ms |
49708 KB |
Output is correct |
20 |
Correct |
7 ms |
49756 KB |
Output is correct |
21 |
Correct |
7 ms |
49756 KB |
Output is correct |
22 |
Execution timed out |
2036 ms |
75192 KB |
Time limit exceeded |
23 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
11 ms |
49756 KB |
Output is correct |
2 |
Correct |
7 ms |
49780 KB |
Output is correct |
3 |
Correct |
8 ms |
49756 KB |
Output is correct |
4 |
Correct |
7 ms |
49756 KB |
Output is correct |
5 |
Correct |
7 ms |
49752 KB |
Output is correct |
6 |
Correct |
7 ms |
49756 KB |
Output is correct |
7 |
Correct |
7 ms |
49756 KB |
Output is correct |
8 |
Correct |
7 ms |
49756 KB |
Output is correct |
9 |
Correct |
7 ms |
49752 KB |
Output is correct |
10 |
Correct |
7 ms |
49756 KB |
Output is correct |
11 |
Correct |
7 ms |
49756 KB |
Output is correct |
12 |
Correct |
7 ms |
49760 KB |
Output is correct |
13 |
Correct |
7 ms |
49756 KB |
Output is correct |
14 |
Correct |
7 ms |
49752 KB |
Output is correct |
15 |
Correct |
7 ms |
49756 KB |
Output is correct |
16 |
Correct |
7 ms |
49696 KB |
Output is correct |
17 |
Correct |
7 ms |
49756 KB |
Output is correct |
18 |
Correct |
8 ms |
49756 KB |
Output is correct |
19 |
Correct |
8 ms |
49708 KB |
Output is correct |
20 |
Correct |
7 ms |
49756 KB |
Output is correct |
21 |
Correct |
7 ms |
49756 KB |
Output is correct |
22 |
Execution timed out |
2036 ms |
75192 KB |
Time limit exceeded |
23 |
Halted |
0 ms |
0 KB |
- |