//Contest: BOI'15 Day 1 Problem 3
//Problem: Net
//Link: https://oj.uz/problem/view/BOI15_net
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("Ofast")
using namespace std;
using namespace __gnu_pbds;
#define lg long long
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define fastio ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define error(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args);
#define endl \n
#define lbound(x, y) lower_bound(x.begin(), x.end(), y)
#define ubound(x, y) upper_bound(x.begin(), x.end(), y)
#define sortasc(v) sort(v.begin(), v.end())
#define sortdesc(v) sort(v.rbegin(), v.rend())
#define custom_array(a,l, r) int _##a[r-l+1]; int*a=_##a-l;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const lg MOD = 1e9+7, N = 5e5+5, M = 1e7+1, SZ = 1e3+1;
/*
bitset<N> primes;
lg pwrs[N], inv[N];
lg fast_power(lg n, lg k)
{
if(!k) return 1;
if(k&1) return (fast_power(n, k-1)*n)%MOD;
lg x = fast_power(n, k/2)%MOD;
return (x*x)%MOD;
}
void sieve()
{
primes.set();
primes[0] = primes[1] = 0;
for(lg i = 2; i < N; i++)
{
if(!primes[i]) continue;
for(lg j = i*i; j < N; j += i)
{
primes[j] = 0;
}
}
return;
}
struct matrix
{
vector<vector<lg>> con = vector<vector<lg>> (SZ, vector<lg> (SZ));
matrix operator *(const matrix& a)
{
matrix product;
for(int i = 0; i < (lg)con.size(); i++)
{
for(int j = 0; j < (lg)a.con[0].size(); j++)
{
for(int k = 0; k < (lg)a.con.size(); k++)
{
product.con[i][j] = (product.con[i][j]+(con[i][k]*a.con[k][j])%MOD)%MOD;
}
}
}
return product;
}
};
void preprocess(lg x)
{
inv[2e5] = fast_power(x, MOD-2);
for(int i = 2e5-1; i > 1; i--)
{
inv[i] = (inv[i+1]*i)%MOD;
}
pwrs[0] = 1;
for(int i = 1; i <= 2e5; i++)
{
pwrs[i] = (pwrs[i]*i)%MOD;
}
return;
}
*/
vector<lg> a, deg(N);
vector<lg> adj[N];
void dfs(lg src, lg par = -1)
{
if(deg[src] == 1) a.push_back(src);
for(auto it : adj[src])
{
if(par == it) continue;
dfs(it, src);
}
return;
}
int main()
{
fastio;
lg n;
cin >> n;
for(int i = 0; i < n-1; i++)
{
lg u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
deg[u]++;
deg[v]++;
}
lg node, mxm_deg = -1;
for(int i = 1; i <= n; i++)
{
if(deg[i] >= 2)
{
mxm_deg = deg[i];
node = i;
}
}
dfs(node);
lg x = a.size();
cout << (x+1)/2 << '\n';
for(int i = 0; i < (x+1)/2; i++)
{
cout << a[i] << ' ' << a[min(i+x/2, x-1)] << '\n';
}
return 0;
}
Compilation message
net.cpp: In function 'int main()':
net.cpp:117:11: warning: variable 'mxm_deg' set but not used [-Wunused-but-set-variable]
117 | lg node, mxm_deg = -1;
| ^~~~~~~
net.cpp:126:5: warning: 'node' may be used uninitialized in this function [-Wmaybe-uninitialized]
126 | dfs(node);
| ~~~^~~~~~
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
9 ms |
15956 KB |
Output is correct |
2 |
Correct |
10 ms |
15936 KB |
Output is correct |
3 |
Correct |
10 ms |
15956 KB |
Output is correct |
4 |
Correct |
9 ms |
15980 KB |
Output is correct |
5 |
Correct |
9 ms |
15964 KB |
Output is correct |
6 |
Correct |
11 ms |
15956 KB |
Output is correct |
7 |
Correct |
8 ms |
15956 KB |
Output is correct |
8 |
Correct |
8 ms |
15956 KB |
Output is correct |
9 |
Correct |
8 ms |
15944 KB |
Output is correct |
10 |
Correct |
8 ms |
15956 KB |
Output is correct |
11 |
Correct |
8 ms |
15956 KB |
Output is correct |
12 |
Correct |
8 ms |
15956 KB |
Output is correct |
13 |
Correct |
8 ms |
15956 KB |
Output is correct |
14 |
Correct |
9 ms |
15956 KB |
Output is correct |
15 |
Correct |
8 ms |
15956 KB |
Output is correct |
16 |
Correct |
8 ms |
15956 KB |
Output is correct |
17 |
Correct |
10 ms |
15956 KB |
Output is correct |
18 |
Correct |
9 ms |
15968 KB |
Output is correct |
19 |
Correct |
11 ms |
15956 KB |
Output is correct |
20 |
Correct |
9 ms |
15956 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
9 ms |
15956 KB |
Output is correct |
2 |
Correct |
10 ms |
15936 KB |
Output is correct |
3 |
Correct |
10 ms |
15956 KB |
Output is correct |
4 |
Correct |
9 ms |
15980 KB |
Output is correct |
5 |
Correct |
9 ms |
15964 KB |
Output is correct |
6 |
Correct |
11 ms |
15956 KB |
Output is correct |
7 |
Correct |
8 ms |
15956 KB |
Output is correct |
8 |
Correct |
8 ms |
15956 KB |
Output is correct |
9 |
Correct |
8 ms |
15944 KB |
Output is correct |
10 |
Correct |
8 ms |
15956 KB |
Output is correct |
11 |
Correct |
8 ms |
15956 KB |
Output is correct |
12 |
Correct |
8 ms |
15956 KB |
Output is correct |
13 |
Correct |
8 ms |
15956 KB |
Output is correct |
14 |
Correct |
9 ms |
15956 KB |
Output is correct |
15 |
Correct |
8 ms |
15956 KB |
Output is correct |
16 |
Correct |
8 ms |
15956 KB |
Output is correct |
17 |
Correct |
10 ms |
15956 KB |
Output is correct |
18 |
Correct |
9 ms |
15968 KB |
Output is correct |
19 |
Correct |
11 ms |
15956 KB |
Output is correct |
20 |
Correct |
9 ms |
15956 KB |
Output is correct |
21 |
Correct |
8 ms |
15956 KB |
Output is correct |
22 |
Correct |
9 ms |
16084 KB |
Output is correct |
23 |
Correct |
10 ms |
16084 KB |
Output is correct |
24 |
Correct |
10 ms |
16004 KB |
Output is correct |
25 |
Correct |
8 ms |
16084 KB |
Output is correct |
26 |
Correct |
9 ms |
16008 KB |
Output is correct |
27 |
Correct |
9 ms |
16008 KB |
Output is correct |
28 |
Correct |
9 ms |
16052 KB |
Output is correct |
29 |
Correct |
11 ms |
16080 KB |
Output is correct |
30 |
Correct |
8 ms |
15956 KB |
Output is correct |
31 |
Correct |
9 ms |
16084 KB |
Output is correct |
32 |
Correct |
8 ms |
15956 KB |
Output is correct |
33 |
Correct |
9 ms |
15956 KB |
Output is correct |
34 |
Correct |
8 ms |
15956 KB |
Output is correct |
35 |
Correct |
8 ms |
15956 KB |
Output is correct |
36 |
Correct |
11 ms |
15948 KB |
Output is correct |
37 |
Correct |
11 ms |
16088 KB |
Output is correct |
38 |
Correct |
9 ms |
15996 KB |
Output is correct |
39 |
Correct |
11 ms |
15912 KB |
Output is correct |
40 |
Correct |
11 ms |
15996 KB |
Output is correct |
41 |
Correct |
9 ms |
15956 KB |
Output is correct |
42 |
Correct |
8 ms |
15996 KB |
Output is correct |
43 |
Correct |
11 ms |
16036 KB |
Output is correct |
44 |
Correct |
9 ms |
15956 KB |
Output is correct |
45 |
Correct |
8 ms |
15956 KB |
Output is correct |
46 |
Correct |
8 ms |
16004 KB |
Output is correct |
47 |
Correct |
9 ms |
15956 KB |
Output is correct |
48 |
Correct |
10 ms |
15896 KB |
Output is correct |
49 |
Correct |
8 ms |
16016 KB |
Output is correct |
50 |
Correct |
9 ms |
15956 KB |
Output is correct |
51 |
Correct |
8 ms |
15956 KB |
Output is correct |
52 |
Correct |
11 ms |
15912 KB |
Output is correct |
53 |
Correct |
9 ms |
16000 KB |
Output is correct |
54 |
Correct |
8 ms |
15956 KB |
Output is correct |
55 |
Correct |
8 ms |
15992 KB |
Output is correct |
56 |
Correct |
8 ms |
15920 KB |
Output is correct |
57 |
Correct |
9 ms |
15996 KB |
Output is correct |
58 |
Correct |
11 ms |
16212 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
9 ms |
15956 KB |
Output is correct |
2 |
Correct |
10 ms |
15936 KB |
Output is correct |
3 |
Correct |
10 ms |
15956 KB |
Output is correct |
4 |
Correct |
9 ms |
15980 KB |
Output is correct |
5 |
Correct |
9 ms |
15964 KB |
Output is correct |
6 |
Correct |
11 ms |
15956 KB |
Output is correct |
7 |
Correct |
8 ms |
15956 KB |
Output is correct |
8 |
Correct |
8 ms |
15956 KB |
Output is correct |
9 |
Correct |
8 ms |
15944 KB |
Output is correct |
10 |
Correct |
8 ms |
15956 KB |
Output is correct |
11 |
Correct |
8 ms |
15956 KB |
Output is correct |
12 |
Correct |
8 ms |
15956 KB |
Output is correct |
13 |
Correct |
8 ms |
15956 KB |
Output is correct |
14 |
Correct |
9 ms |
15956 KB |
Output is correct |
15 |
Correct |
8 ms |
15956 KB |
Output is correct |
16 |
Correct |
8 ms |
15956 KB |
Output is correct |
17 |
Correct |
10 ms |
15956 KB |
Output is correct |
18 |
Correct |
9 ms |
15968 KB |
Output is correct |
19 |
Correct |
11 ms |
15956 KB |
Output is correct |
20 |
Correct |
9 ms |
15956 KB |
Output is correct |
21 |
Correct |
8 ms |
15956 KB |
Output is correct |
22 |
Correct |
9 ms |
16084 KB |
Output is correct |
23 |
Correct |
10 ms |
16084 KB |
Output is correct |
24 |
Correct |
10 ms |
16004 KB |
Output is correct |
25 |
Correct |
8 ms |
16084 KB |
Output is correct |
26 |
Correct |
9 ms |
16008 KB |
Output is correct |
27 |
Correct |
9 ms |
16008 KB |
Output is correct |
28 |
Correct |
9 ms |
16052 KB |
Output is correct |
29 |
Correct |
11 ms |
16080 KB |
Output is correct |
30 |
Correct |
8 ms |
15956 KB |
Output is correct |
31 |
Correct |
9 ms |
16084 KB |
Output is correct |
32 |
Correct |
8 ms |
15956 KB |
Output is correct |
33 |
Correct |
9 ms |
15956 KB |
Output is correct |
34 |
Correct |
8 ms |
15956 KB |
Output is correct |
35 |
Correct |
8 ms |
15956 KB |
Output is correct |
36 |
Correct |
11 ms |
15948 KB |
Output is correct |
37 |
Correct |
11 ms |
16088 KB |
Output is correct |
38 |
Correct |
9 ms |
15996 KB |
Output is correct |
39 |
Correct |
11 ms |
15912 KB |
Output is correct |
40 |
Correct |
11 ms |
15996 KB |
Output is correct |
41 |
Correct |
9 ms |
15956 KB |
Output is correct |
42 |
Correct |
8 ms |
15996 KB |
Output is correct |
43 |
Correct |
11 ms |
16036 KB |
Output is correct |
44 |
Correct |
9 ms |
15956 KB |
Output is correct |
45 |
Correct |
8 ms |
15956 KB |
Output is correct |
46 |
Correct |
8 ms |
16004 KB |
Output is correct |
47 |
Correct |
9 ms |
15956 KB |
Output is correct |
48 |
Correct |
10 ms |
15896 KB |
Output is correct |
49 |
Correct |
8 ms |
16016 KB |
Output is correct |
50 |
Correct |
9 ms |
15956 KB |
Output is correct |
51 |
Correct |
8 ms |
15956 KB |
Output is correct |
52 |
Correct |
11 ms |
15912 KB |
Output is correct |
53 |
Correct |
9 ms |
16000 KB |
Output is correct |
54 |
Correct |
8 ms |
15956 KB |
Output is correct |
55 |
Correct |
8 ms |
15992 KB |
Output is correct |
56 |
Correct |
8 ms |
15920 KB |
Output is correct |
57 |
Correct |
9 ms |
15996 KB |
Output is correct |
58 |
Correct |
11 ms |
16212 KB |
Output is correct |
59 |
Correct |
379 ms |
44344 KB |
Output is correct |
60 |
Correct |
498 ms |
47288 KB |
Output is correct |
61 |
Correct |
9 ms |
15956 KB |
Output is correct |
62 |
Correct |
11 ms |
15948 KB |
Output is correct |
63 |
Correct |
347 ms |
40540 KB |
Output is correct |
64 |
Correct |
13 ms |
16212 KB |
Output is correct |
65 |
Correct |
19 ms |
17620 KB |
Output is correct |
66 |
Correct |
168 ms |
28092 KB |
Output is correct |
67 |
Correct |
543 ms |
57220 KB |
Output is correct |
68 |
Correct |
526 ms |
52412 KB |
Output is correct |
69 |
Correct |
16 ms |
17036 KB |
Output is correct |
70 |
Correct |
111 ms |
27224 KB |
Output is correct |
71 |
Correct |
403 ms |
49688 KB |
Output is correct |
72 |
Correct |
362 ms |
48128 KB |
Output is correct |
73 |
Correct |
124 ms |
23968 KB |
Output is correct |
74 |
Correct |
511 ms |
45096 KB |
Output is correct |
75 |
Correct |
45 ms |
19524 KB |
Output is correct |
76 |
Correct |
359 ms |
49240 KB |
Output is correct |
77 |
Correct |
411 ms |
49384 KB |
Output is correct |
78 |
Correct |
44 ms |
19476 KB |
Output is correct |
79 |
Correct |
558 ms |
46972 KB |
Output is correct |
80 |
Correct |
11 ms |
16264 KB |
Output is correct |
81 |
Correct |
176 ms |
26480 KB |
Output is correct |
82 |
Correct |
466 ms |
47104 KB |
Output is correct |
83 |
Correct |
522 ms |
45080 KB |
Output is correct |
84 |
Correct |
559 ms |
45024 KB |
Output is correct |
85 |
Correct |
525 ms |
45000 KB |
Output is correct |
86 |
Correct |
527 ms |
47332 KB |
Output is correct |
87 |
Correct |
496 ms |
47320 KB |
Output is correct |