oj.uz

Submission #931646

# Submission time Handle Problem Language Result Execution time Memory
931646 2024-02-22T07:45:53 Z vjudge1 Network (BOI15_net) C++17
63 / 100
 303 ms 27484 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 = 2'000 + 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) {
      |        ~~~~~~~~~~~~~^~~~~~~~~~~~~

Subtask #1
18.0 / 18.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 1 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 0 ms 348 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 0 ms 348 KB Output is correct

Subtask #2
45.0 / 45.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 1 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 0 ms 348 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 0 ms 348 KB Output is correct
21 Correct 1 ms 348 KB Output is correct
22 Correct 292 ms 27484 KB Output is correct
23 Correct 248 ms 25512 KB Output is correct
24 Correct 288 ms 25544 KB Output is correct
25 Correct 102 ms 14784 KB Output is correct
26 Correct 70 ms 8396 KB Output is correct
27 Correct 185 ms 14768 KB Output is correct
28 Correct 162 ms 13904 KB Output is correct
29 Correct 97 ms 8804 KB Output is correct
30 Correct 0 ms 344 KB Output is correct
31 Correct 183 ms 13244 KB Output is correct
32 Correct 0 ms 348 KB Output is correct
33 Correct 0 ms 348 KB Output is correct
34 Correct 1 ms 348 KB Output is correct
35 Correct 0 ms 348 KB Output is correct
36 Correct 1 ms 600 KB Output is correct
37 Correct 1 ms 604 KB Output is correct
38 Correct 1 ms 604 KB Output is correct
39 Correct 0 ms 348 KB Output is correct
40 Correct 1 ms 516 KB Output is correct
41 Correct 1 ms 604 KB Output is correct
42 Correct 16 ms 2264 KB Output is correct
43 Correct 58 ms 8908 KB Output is correct
44 Correct 1 ms 348 KB Output is correct
45 Correct 5 ms 1052 KB Output is correct
46 Correct 26 ms 2264 KB Output is correct
47 Correct 0 ms 348 KB Output is correct
48 Correct 4 ms 1068 KB Output is correct
49 Correct 59 ms 8656 KB Output is correct
50 Correct 0 ms 344 KB Output is correct
51 Correct 1 ms 348 KB Output is correct
52 Correct 1 ms 604 KB Output is correct
53 Correct 14 ms 1624 KB Output is correct
54 Correct 1 ms 344 KB Output is correct
55 Correct 7 ms 1500 KB Output is correct
56 Correct 1 ms 604 KB Output is correct
57 Correct 17 ms 2260 KB Output is correct
58 Correct 303 ms 27056 KB Output is correct

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 1 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 1 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct
15 Correct 0 ms 348 KB Output is correct
16 Correct 0 ms 344 KB Output is correct
17 Correct 0 ms 348 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 0 ms 348 KB Output is correct
20 Correct 0 ms 348 KB Output is correct
21 Correct 1 ms 348 KB Output is correct
22 Correct 292 ms 27484 KB Output is correct
23 Correct 248 ms 25512 KB Output is correct
24 Correct 288 ms 25544 KB Output is correct
25 Correct 102 ms 14784 KB Output is correct
26 Correct 70 ms 8396 KB Output is correct
27 Correct 185 ms 14768 KB Output is correct
28 Correct 162 ms 13904 KB Output is correct
29 Correct 97 ms 8804 KB Output is correct
30 Correct 0 ms 344 KB Output is correct
31 Correct 183 ms 13244 KB Output is correct
32 Correct 0 ms 348 KB Output is correct
33 Correct 0 ms 348 KB Output is correct
34 Correct 1 ms 348 KB Output is correct
35 Correct 0 ms 348 KB Output is correct
36 Correct 1 ms 600 KB Output is correct
37 Correct 1 ms 604 KB Output is correct
38 Correct 1 ms 604 KB Output is correct
39 Correct 0 ms 348 KB Output is correct
40 Correct 1 ms 516 KB Output is correct
41 Correct 1 ms 604 KB Output is correct
42 Correct 16 ms 2264 KB Output is correct
43 Correct 58 ms 8908 KB Output is correct
44 Correct 1 ms 348 KB Output is correct
45 Correct 5 ms 1052 KB Output is correct
46 Correct 26 ms 2264 KB Output is correct
47 Correct 0 ms 348 KB Output is correct
48 Correct 4 ms 1068 KB Output is correct
49 Correct 59 ms 8656 KB Output is correct
50 Correct 0 ms 344 KB Output is correct
51 Correct 1 ms 348 KB Output is correct
52 Correct 1 ms 604 KB Output is correct
53 Correct 14 ms 1624 KB Output is correct
54 Correct 1 ms 344 KB Output is correct
55 Correct 7 ms 1500 KB Output is correct
56 Correct 1 ms 604 KB Output is correct
57 Correct 17 ms 2260 KB Output is correct
58 Correct 303 ms 27056 KB Output is correct
59 Runtime error 1 ms 604 KB Execution killed with signal 11
60 Halted 0 ms 0 KB -