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Submission #633978

# Submission time Handle Problem Language Result Execution time Memory
633978 2022-08-23T15:02:20 Z radal Network (BOI15_net) C++17
100 / 100
 466 ms 37132 KB 
#include <bits/stdc++.h>
#pragma GCC target("sse,sse2")
#pragma GCC optimize("unroll-loops,O3")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pll;
constexpr int N = 5e5+20,mod = 1e9+7,inf = 1e9+10;
inline int mkay(int a,int b){
    if (a+b >= mod) return a+b-mod;
    if (a+b < 0) return a+b+mod;
    return a+b;
}
 
inline int poww(int a,int k){
    if (k < 0) return 0;
    int z = 1;
    while (k){
        if (k&1) z = 1ll*z*a%mod;
        a = 1ll*a*a%mod;
        k /= 2;
    } 
    return z; 
}

vector<int> adj[N],ve;
int tin[N],T;

bool cmp(int u,int v){
    return (tin[u] < tin[v]);
}

void dfs(int v,int p){
    tin[v] = T++;
    for(int u : adj[v]) if (u != p) dfs(u,v);
}
int main(){
    ios_base :: sync_with_stdio(0); cin.tie(0);
    int n,ans = 0;
    cin >> n;
    rep(i,1,n){
        int u,v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
    dfs(1,0);
    rep(i,1,n+1) if (adj[i].size() == 1){
        ans++;
        ve.pb(i);
    }
    int t = (ans+1)/2;
    cout << t << endl;
    sort(all(ve),cmp);
    rep(i,0,ans){
        if (i >= t) break;
        if (i+t == ans){
            cout << ve[i] << ' ' << ve[0] << endl;
            break;
        }
        cout << ve[i] << ' ' << ve[i+t] << endl;
    }
}

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 6 ms 11988 KB Output is correct
4 Correct 7 ms 11964 KB Output is correct
5 Correct 7 ms 11988 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 7 ms 11988 KB Output is correct
8 Correct 7 ms 11988 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 6 ms 11988 KB Output is correct
11 Correct 6 ms 11988 KB Output is correct
12 Correct 6 ms 11988 KB Output is correct
13 Correct 6 ms 11988 KB Output is correct
14 Correct 6 ms 11988 KB Output is correct
15 Correct 7 ms 12064 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 7 ms 11988 KB Output is correct
18 Correct 7 ms 11988 KB Output is correct
19 Correct 6 ms 11960 KB Output is correct
20 Correct 6 ms 11988 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 6 ms 11988 KB Output is correct
4 Correct 7 ms 11964 KB Output is correct
5 Correct 7 ms 11988 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 7 ms 11988 KB Output is correct
8 Correct 7 ms 11988 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 6 ms 11988 KB Output is correct
11 Correct 6 ms 11988 KB Output is correct
12 Correct 6 ms 11988 KB Output is correct
13 Correct 6 ms 11988 KB Output is correct
14 Correct 6 ms 11988 KB Output is correct
15 Correct 7 ms 12064 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 7 ms 11988 KB Output is correct
18 Correct 7 ms 11988 KB Output is correct
19 Correct 6 ms 11960 KB Output is correct
20 Correct 6 ms 11988 KB Output is correct
21 Correct 7 ms 11988 KB Output is correct
22 Correct 7 ms 12116 KB Output is correct
23 Correct 6 ms 12116 KB Output is correct
24 Correct 7 ms 12116 KB Output is correct
25 Correct 6 ms 12116 KB Output is correct
26 Correct 8 ms 12116 KB Output is correct
27 Correct 8 ms 12116 KB Output is correct
28 Correct 7 ms 12116 KB Output is correct
29 Correct 7 ms 12116 KB Output is correct
30 Correct 6 ms 11988 KB Output is correct
31 Correct 7 ms 12116 KB Output is correct
32 Correct 6 ms 11988 KB Output is correct
33 Correct 8 ms 11988 KB Output is correct
34 Correct 7 ms 11988 KB Output is correct
35 Correct 6 ms 11988 KB Output is correct
36 Correct 7 ms 12064 KB Output is correct
37 Correct 6 ms 11988 KB Output is correct
38 Correct 6 ms 12116 KB Output is correct
39 Correct 6 ms 11988 KB Output is correct
40 Correct 8 ms 12068 KB Output is correct
41 Correct 7 ms 11988 KB Output is correct
42 Correct 8 ms 12068 KB Output is correct
43 Correct 6 ms 12116 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 8 ms 11988 KB Output is correct
46 Correct 6 ms 11988 KB Output is correct
47 Correct 6 ms 11988 KB Output is correct
48 Correct 9 ms 12084 KB Output is correct
49 Correct 7 ms 12116 KB Output is correct
50 Correct 6 ms 11988 KB Output is correct
51 Correct 6 ms 11988 KB Output is correct
52 Correct 6 ms 11988 KB Output is correct
53 Correct 6 ms 11988 KB Output is correct
54 Correct 6 ms 11988 KB Output is correct
55 Correct 6 ms 11988 KB Output is correct
56 Correct 6 ms 11988 KB Output is correct
57 Correct 6 ms 11988 KB Output is correct
58 Correct 7 ms 12116 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11988 KB Output is correct
2 Correct 6 ms 11988 KB Output is correct
3 Correct 6 ms 11988 KB Output is correct
4 Correct 7 ms 11964 KB Output is correct
5 Correct 7 ms 11988 KB Output is correct
6 Correct 6 ms 11988 KB Output is correct
7 Correct 7 ms 11988 KB Output is correct
8 Correct 7 ms 11988 KB Output is correct
9 Correct 6 ms 11988 KB Output is correct
10 Correct 6 ms 11988 KB Output is correct
11 Correct 6 ms 11988 KB Output is correct
12 Correct 6 ms 11988 KB Output is correct
13 Correct 6 ms 11988 KB Output is correct
14 Correct 6 ms 11988 KB Output is correct
15 Correct 7 ms 12064 KB Output is correct
16 Correct 6 ms 11988 KB Output is correct
17 Correct 7 ms 11988 KB Output is correct
18 Correct 7 ms 11988 KB Output is correct
19 Correct 6 ms 11960 KB Output is correct
20 Correct 6 ms 11988 KB Output is correct
21 Correct 7 ms 11988 KB Output is correct
22 Correct 7 ms 12116 KB Output is correct
23 Correct 6 ms 12116 KB Output is correct
24 Correct 7 ms 12116 KB Output is correct
25 Correct 6 ms 12116 KB Output is correct
26 Correct 8 ms 12116 KB Output is correct
27 Correct 8 ms 12116 KB Output is correct
28 Correct 7 ms 12116 KB Output is correct
29 Correct 7 ms 12116 KB Output is correct
30 Correct 6 ms 11988 KB Output is correct
31 Correct 7 ms 12116 KB Output is correct
32 Correct 6 ms 11988 KB Output is correct
33 Correct 8 ms 11988 KB Output is correct
34 Correct 7 ms 11988 KB Output is correct
35 Correct 6 ms 11988 KB Output is correct
36 Correct 7 ms 12064 KB Output is correct
37 Correct 6 ms 11988 KB Output is correct
38 Correct 6 ms 12116 KB Output is correct
39 Correct 6 ms 11988 KB Output is correct
40 Correct 8 ms 12068 KB Output is correct
41 Correct 7 ms 11988 KB Output is correct
42 Correct 8 ms 12068 KB Output is correct
43 Correct 6 ms 12116 KB Output is correct
44 Correct 6 ms 11988 KB Output is correct
45 Correct 8 ms 11988 KB Output is correct
46 Correct 6 ms 11988 KB Output is correct
47 Correct 6 ms 11988 KB Output is correct
48 Correct 9 ms 12084 KB Output is correct
49 Correct 7 ms 12116 KB Output is correct
50 Correct 6 ms 11988 KB Output is correct
51 Correct 6 ms 11988 KB Output is correct
52 Correct 6 ms 11988 KB Output is correct
53 Correct 6 ms 11988 KB Output is correct
54 Correct 6 ms 11988 KB Output is correct
55 Correct 6 ms 11988 KB Output is correct
56 Correct 6 ms 11988 KB Output is correct
57 Correct 6 ms 11988 KB Output is correct
58 Correct 7 ms 12116 KB Output is correct
59 Correct 330 ms 31748 KB Output is correct
60 Correct 410 ms 34072 KB Output is correct
61 Correct 6 ms 11988 KB Output is correct
62 Correct 7 ms 11988 KB Output is correct
63 Correct 290 ms 29860 KB Output is correct
64 Correct 8 ms 12244 KB Output is correct
65 Correct 14 ms 13268 KB Output is correct
66 Correct 131 ms 22524 KB Output is correct
67 Correct 388 ms 36252 KB Output is correct
68 Correct 399 ms 36816 KB Output is correct
69 Correct 13 ms 12756 KB Output is correct
70 Correct 109 ms 19752 KB Output is correct
71 Correct 297 ms 37096 KB Output is correct
72 Correct 344 ms 36272 KB Output is correct
73 Correct 88 ms 17860 KB Output is correct
74 Correct 406 ms 33024 KB Output is correct
75 Correct 37 ms 14804 KB Output is correct
76 Correct 314 ms 36696 KB Output is correct
77 Correct 307 ms 37132 KB Output is correct
78 Correct 29 ms 14560 KB Output is correct
79 Correct 413 ms 35236 KB Output is correct
80 Correct 8 ms 12244 KB Output is correct
81 Correct 122 ms 19844 KB Output is correct
82 Correct 352 ms 35056 KB Output is correct
83 Correct 421 ms 32988 KB Output is correct
84 Correct 395 ms 32920 KB Output is correct
85 Correct 386 ms 32932 KB Output is correct
86 Correct 383 ms 34080 KB Output is correct
87 Correct 466 ms 34188 KB Output is correct