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Submission #869435

# Submission time Handle Problem Language Result Execution time Memory
869435 2023-11-04T10:30:17 Z LeThanhMinh Network (BOI15_net) C++14
100 / 100
 364 ms 52516 KB 
/*CP template version 3.0 - Laconic*/

#include <bits/stdc++.h>

#define ii pair<int, int>
#define fs first
#define sc second

//use struct instead of pair<int, ii>

#define int long long

#define show(v) {for (auto i : v) cout << i << " "; cout << endl;}
#define showlr(v, l, r) {for (int i = l; i <= r; i++) cout << v[i] << " "; cout << endl;}
#define all(v) v.begin(), v.end()
#define SUnique(v) {sort(all(v)); v.erase(unique(all(v)), v.end());}
#define forlr(i, l, r) for (int i = l; i <= r; i++)
#define forrl(i, r, l) for (int i = r; i >= l; i--)

#pragma GCC Optimize("O2")
#define endl "\n"
#define precise(x) cout << fixed << setprecision(x);

using namespace std;

const int N = 5e5 + 100;
const int MOD = 1e9 + 7;
const int INF = 1e9;
const int LOG = 25;
const long long LINF = 1e15 + 100;

const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, -1, 0, 1};
 
ostream& operator << (ostream &os, ii a) {
    
    os << a.fs << ' ' << a.sc;
    return os;
    
}

int binPow(int a, int b, int m = LLONG_MAX) {
    
    int prod = 1;
    a %= m;
    
    while (b) {
        
        if (b & 1) prod = prod * a % m;
        a = a * a % m;
        b /= 2;
        
    }
    
    return prod;
    
}

void setIO(string s) {
    
    if (s.empty()) return;
    
    freopen((s + ".inp").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
    
}

//Try Brute Force (maybe there is a pattern)
//Try DP (Weird constraints (sum of all elements <= 10000), small constraints)
//Try Graph (a pair of number, condition between elements)
//Try Geometry (Same as graph, for coordinate)

//Try switching between problem
//Put down what you have on paper
//IMPORTANT: WRITE DOWN THE FORMULA

int n, m, q, k;
int arr[N];
vector<int> adj[N];

mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());

vector<int> leaf;

void dfs(int u, int pre) {
	
	if (adj[u].size() == 1) {
		
		leaf.push_back(u);
		if (u != pre) return;
		
	}
	
	for (int v : adj[u]) {
		
		if (v == pre) continue;
		dfs(v, u);
		
	}
	
}

int deg[N];
ii edges[N];

void solve() {
	
	cin >> n;
	
	forlr(i, 1, n - 1) {
		
		int u, v; cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
		
	}
	
	dfs(1, 1);
	
	vector<ii> res;
	
	int sz = leaf.size();
	if (sz == 2) {
		
		cout << 1 << endl;
		cout << leaf[0] << " " << leaf[1] << endl;
		return;
		
	}
	
	if (sz <= 1) {
		
		cout << 0 << endl;
		return;
		
	}
	
	forlr(i, 0, (sz - 1) / 2) res.push_back({leaf[i], leaf[i + sz / 2]});
	
	cout << res.size() << endl;
	for (ii i : res) cout << i << endl;
    
}

signed main() {
    
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);    
    
    int T = 1;
    
    bool multiTest = 0;
    if (multiTest) cin >> T;
    
    while (T--) {
        
        solve();
    
    }
    
}

Compilation message

net.cpp:20: warning: ignoring '#pragma GCC Optimize' [-Wunknown-pragmas]
   20 | #pragma GCC Optimize("O2")
      | 
net.cpp: In function 'void setIO(std::string)':
net.cpp:63:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |     freopen((s + ".inp").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net.cpp:64:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   64 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 14684 KB Output is correct
2 Correct 3 ms 14684 KB Output is correct
3 Correct 2 ms 14684 KB Output is correct
4 Correct 3 ms 14684 KB Output is correct
5 Correct 3 ms 14684 KB Output is correct
6 Correct 3 ms 14684 KB Output is correct
7 Correct 3 ms 14684 KB Output is correct
8 Correct 3 ms 14684 KB Output is correct
9 Correct 3 ms 14684 KB Output is correct
10 Correct 3 ms 14684 KB Output is correct
11 Correct 3 ms 14684 KB Output is correct
12 Correct 3 ms 14684 KB Output is correct
13 Correct 3 ms 14680 KB Output is correct
14 Correct 3 ms 14684 KB Output is correct
15 Correct 2 ms 14684 KB Output is correct
16 Correct 3 ms 14684 KB Output is correct
17 Correct 3 ms 14684 KB Output is correct
18 Correct 3 ms 14684 KB Output is correct
19 Correct 3 ms 14684 KB Output is correct
20 Correct 3 ms 14680 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 14684 KB Output is correct
2 Correct 3 ms 14684 KB Output is correct
3 Correct 2 ms 14684 KB Output is correct
4 Correct 3 ms 14684 KB Output is correct
5 Correct 3 ms 14684 KB Output is correct
6 Correct 3 ms 14684 KB Output is correct
7 Correct 3 ms 14684 KB Output is correct
8 Correct 3 ms 14684 KB Output is correct
9 Correct 3 ms 14684 KB Output is correct
10 Correct 3 ms 14684 KB Output is correct
11 Correct 3 ms 14684 KB Output is correct
12 Correct 3 ms 14684 KB Output is correct
13 Correct 3 ms 14680 KB Output is correct
14 Correct 3 ms 14684 KB Output is correct
15 Correct 2 ms 14684 KB Output is correct
16 Correct 3 ms 14684 KB Output is correct
17 Correct 3 ms 14684 KB Output is correct
18 Correct 3 ms 14684 KB Output is correct
19 Correct 3 ms 14684 KB Output is correct
20 Correct 3 ms 14680 KB Output is correct
21 Correct 2 ms 14680 KB Output is correct
22 Correct 3 ms 14940 KB Output is correct
23 Correct 3 ms 14940 KB Output is correct
24 Correct 3 ms 14940 KB Output is correct
25 Correct 3 ms 14940 KB Output is correct
26 Correct 3 ms 14684 KB Output is correct
27 Correct 3 ms 14940 KB Output is correct
28 Correct 3 ms 14940 KB Output is correct
29 Correct 3 ms 14684 KB Output is correct
30 Correct 3 ms 14680 KB Output is correct
31 Correct 4 ms 14908 KB Output is correct
32 Correct 3 ms 14684 KB Output is correct
33 Correct 3 ms 14684 KB Output is correct
34 Correct 3 ms 14684 KB Output is correct
35 Correct 3 ms 14680 KB Output is correct
36 Correct 3 ms 14684 KB Output is correct
37 Correct 3 ms 14684 KB Output is correct
38 Correct 3 ms 14684 KB Output is correct
39 Correct 3 ms 14684 KB Output is correct
40 Correct 3 ms 14688 KB Output is correct
41 Correct 3 ms 14836 KB Output is correct
42 Correct 3 ms 14688 KB Output is correct
43 Correct 3 ms 14688 KB Output is correct
44 Correct 4 ms 14688 KB Output is correct
45 Correct 3 ms 14880 KB Output is correct
46 Correct 3 ms 14684 KB Output is correct
47 Correct 3 ms 14684 KB Output is correct
48 Correct 3 ms 14684 KB Output is correct
49 Correct 3 ms 14684 KB Output is correct
50 Correct 2 ms 14684 KB Output is correct
51 Correct 3 ms 14684 KB Output is correct
52 Correct 3 ms 14684 KB Output is correct
53 Correct 3 ms 14684 KB Output is correct
54 Correct 2 ms 14684 KB Output is correct
55 Correct 3 ms 14684 KB Output is correct
56 Correct 3 ms 14936 KB Output is correct
57 Correct 3 ms 14684 KB Output is correct
58 Correct 4 ms 14940 KB Output is correct

Subtask #3
37.0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 14684 KB Output is correct
2 Correct 3 ms 14684 KB Output is correct
3 Correct 2 ms 14684 KB Output is correct
4 Correct 3 ms 14684 KB Output is correct
5 Correct 3 ms 14684 KB Output is correct
6 Correct 3 ms 14684 KB Output is correct
7 Correct 3 ms 14684 KB Output is correct
8 Correct 3 ms 14684 KB Output is correct
9 Correct 3 ms 14684 KB Output is correct
10 Correct 3 ms 14684 KB Output is correct
11 Correct 3 ms 14684 KB Output is correct
12 Correct 3 ms 14684 KB Output is correct
13 Correct 3 ms 14680 KB Output is correct
14 Correct 3 ms 14684 KB Output is correct
15 Correct 2 ms 14684 KB Output is correct
16 Correct 3 ms 14684 KB Output is correct
17 Correct 3 ms 14684 KB Output is correct
18 Correct 3 ms 14684 KB Output is correct
19 Correct 3 ms 14684 KB Output is correct
20 Correct 3 ms 14680 KB Output is correct
21 Correct 2 ms 14680 KB Output is correct
22 Correct 3 ms 14940 KB Output is correct
23 Correct 3 ms 14940 KB Output is correct
24 Correct 3 ms 14940 KB Output is correct
25 Correct 3 ms 14940 KB Output is correct
26 Correct 3 ms 14684 KB Output is correct
27 Correct 3 ms 14940 KB Output is correct
28 Correct 3 ms 14940 KB Output is correct
29 Correct 3 ms 14684 KB Output is correct
30 Correct 3 ms 14680 KB Output is correct
31 Correct 4 ms 14908 KB Output is correct
32 Correct 3 ms 14684 KB Output is correct
33 Correct 3 ms 14684 KB Output is correct
34 Correct 3 ms 14684 KB Output is correct
35 Correct 3 ms 14680 KB Output is correct
36 Correct 3 ms 14684 KB Output is correct
37 Correct 3 ms 14684 KB Output is correct
38 Correct 3 ms 14684 KB Output is correct
39 Correct 3 ms 14684 KB Output is correct
40 Correct 3 ms 14688 KB Output is correct
41 Correct 3 ms 14836 KB Output is correct
42 Correct 3 ms 14688 KB Output is correct
43 Correct 3 ms 14688 KB Output is correct
44 Correct 4 ms 14688 KB Output is correct
45 Correct 3 ms 14880 KB Output is correct
46 Correct 3 ms 14684 KB Output is correct
47 Correct 3 ms 14684 KB Output is correct
48 Correct 3 ms 14684 KB Output is correct
49 Correct 3 ms 14684 KB Output is correct
50 Correct 2 ms 14684 KB Output is correct
51 Correct 3 ms 14684 KB Output is correct
52 Correct 3 ms 14684 KB Output is correct
53 Correct 3 ms 14684 KB Output is correct
54 Correct 2 ms 14684 KB Output is correct
55 Correct 3 ms 14684 KB Output is correct
56 Correct 3 ms 14936 KB Output is correct
57 Correct 3 ms 14684 KB Output is correct
58 Correct 4 ms 14940 KB Output is correct
59 Correct 213 ms 47296 KB Output is correct
60 Correct 267 ms 51648 KB Output is correct
61 Correct 3 ms 14680 KB Output is correct
62 Correct 3 ms 14684 KB Output is correct
63 Correct 202 ms 45468 KB Output is correct
64 Correct 4 ms 15192 KB Output is correct
65 Correct 10 ms 16728 KB Output is correct
66 Correct 62 ms 30432 KB Output is correct
67 Correct 338 ms 49428 KB Output is correct
68 Correct 364 ms 51656 KB Output is correct
69 Correct 7 ms 15960 KB Output is correct
70 Correct 54 ms 27224 KB Output is correct
71 Correct 176 ms 52412 KB Output is correct
72 Correct 195 ms 52276 KB Output is correct
73 Correct 57 ms 23672 KB Output is correct
74 Correct 276 ms 45836 KB Output is correct
75 Correct 19 ms 18772 KB Output is correct
76 Correct 217 ms 51744 KB Output is correct
77 Correct 191 ms 52060 KB Output is correct
78 Correct 19 ms 18512 KB Output is correct
79 Correct 335 ms 47940 KB Output is correct
80 Correct 6 ms 15196 KB Output is correct
81 Correct 72 ms 26316 KB Output is correct
82 Correct 219 ms 52028 KB Output is correct
83 Correct 272 ms 45928 KB Output is correct
84 Correct 254 ms 45884 KB Output is correct
85 Correct 325 ms 45732 KB Output is correct
86 Correct 297 ms 52516 KB Output is correct
87 Correct 307 ms 52492 KB Output is correct