oj.uz

Submission #805724

# Submission time Handle Problem Language Result Execution time Memory
805724 2023-08-03T21:46:43 Z YesPy Cheap flights (LMIO18_pigus_skrydziai) C++17
0 / 100
 500 ms 194748 KB 
#include <bits/stdc++.h>

#define ff first
#define ss second
#define tcT template<class T
#define fastio ios::sync_with_stdio(false);cin.tie(nullptr);
#define ln '\n'
#define nwln cout<<ln;

using namespace std;

tcT> using vr = vector<T>;
using pi = pair<int, int>;
using vi = vr<int>;
using vpi = vr<pi>;
using ll = long long;
using oo = bool;

#define maxs(i, j) (i = max(i, j))
#define fri(i,a,b) for(int i=(a); i<(b); ++i)
#define each(x, a) for(auto& x: a)

#define sz(x) int((x).size())
#define phb push_back
#define eb emplace_back

const int MX = (int) 3e5+3;
ll N, M, ans;
oo used[MX];
set<int> orz[MX];
vpi adj[MX];

inline void dfs(int u) {
	used[u] = true;
	ll res = 0, xam = 0, U, idx = 0;

	map<int, int> cur;

	each(x, adj[u]) {
		cur[x.ff] = idx++;
		res += x.ss;
		if(xam < x.ss) U = x.ff, xam = x.ss;
	}

	maxs(ans, res);
	// idk if this "if" is necessary
	if(!used[U]) {
		each(x, adj[U]) {
			if(!orz[u].count(x.ff)) continue;
			maxs(ans, xam + x.ss + adj[u][cur[x.ff]].ss);
		}
	}

	each(x, adj[u]) {
		if(!used[x.ff]) dfs(x.ff);
	}
}

int main()
{
	fastio
	cin>>N>>M;

	while(M--) {
		int u, v, w;
		cin>>u>>v>>w;
		adj[u].eb(v, w);
		adj[v].eb(u, w);
		orz[u].insert(v);
		orz[v].insert(u);
	}

	fri(i,1,N+1) {
		if(used[i]) continue;
		dfs(i);
	}

	cout<<ans<<ln;

	return 0;
}

/*
Wow, beautiful trick
Two possible types: star or triangle
Stars are easy, bottleneck are the triangles

What I do is, if I'm on node v then between all its edges I choose the
greatest one and try to match the rest... it can be proved it's correct

Suppose the answer is not correct and let the max-weight triangle be
p, q -> a
q, r -> b
r, p -> c

Then, we're assuming there exists
p, P -> greater than c, a but less than b
q, Q -> greater than a, b but less than c
r, R -> greater than b, c but less than a

Contradiction! We're done :D
*/

Compilation message

pigus_skrydziai.cpp: In function 'void dfs(int)':
pigus_skrydziai.cpp:35:23: warning: 'U' may be used uninitialized in this function [-Wmaybe-uninitialized]
   35 |  ll res = 0, xam = 0, U, idx = 0;
      |                       ^

Subtask #1
0 / 12.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 21332 KB Output is correct
2 Correct 10 ms 21460 KB Output is correct
3 Correct 9 ms 21460 KB Output is correct
4 Correct 10 ms 21388 KB Output is correct
5 Correct 10 ms 21392 KB Output is correct
6 Correct 21 ms 25864 KB Output is correct
7 Correct 10 ms 21460 KB Output is correct
8 Correct 9 ms 21456 KB Output is correct
9 Correct 11 ms 21448 KB Output is correct
10 Correct 11 ms 21460 KB Output is correct
11 Correct 9 ms 21460 KB Output is correct
12 Correct 10 ms 21460 KB Output is correct
13 Correct 9 ms 21456 KB Output is correct
14 Correct 9 ms 21384 KB Output is correct
15 Correct 11 ms 21408 KB Output is correct
16 Correct 10 ms 21460 KB Output is correct
17 Correct 11 ms 21448 KB Output is correct
18 Correct 11 ms 21596 KB Output is correct
19 Correct 11 ms 21860 KB Output is correct
20 Correct 11 ms 21460 KB Output is correct
21 Runtime error 25 ms 43208 KB Execution killed with signal 11
22 Halted 0 ms 0 KB -

Subtask #2
0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 21332 KB Output is correct
2 Correct 10 ms 21460 KB Output is correct
3 Correct 9 ms 21460 KB Output is correct
4 Correct 10 ms 21388 KB Output is correct
5 Correct 10 ms 21392 KB Output is correct
6 Correct 21 ms 25864 KB Output is correct
7 Correct 10 ms 21460 KB Output is correct
8 Correct 9 ms 21456 KB Output is correct
9 Correct 11 ms 21448 KB Output is correct
10 Correct 11 ms 21460 KB Output is correct
11 Correct 9 ms 21460 KB Output is correct
12 Correct 10 ms 21460 KB Output is correct
13 Correct 9 ms 21456 KB Output is correct
14 Correct 9 ms 21384 KB Output is correct
15 Correct 11 ms 21408 KB Output is correct
16 Correct 10 ms 21460 KB Output is correct
17 Correct 11 ms 21448 KB Output is correct
18 Correct 11 ms 21596 KB Output is correct
19 Correct 11 ms 21860 KB Output is correct
20 Correct 11 ms 21460 KB Output is correct
21 Runtime error 25 ms 43208 KB Execution killed with signal 11
22 Halted 0 ms 0 KB -

Subtask #3
0 / 16.0

# Verdict Execution time Memory Grader output
1 Correct 148 ms 47452 KB Output is correct
2 Correct 299 ms 63788 KB Output is correct
3 Correct 77 ms 35360 KB Output is correct
4 Correct 188 ms 51656 KB Output is correct
5 Runtime error 500 ms 194748 KB Execution killed with signal 11
6 Halted 0 ms 0 KB -

Subtask #4
0 / 47.0

# Verdict Execution time Memory Grader output
1 Correct 148 ms 47452 KB Output is correct
2 Correct 299 ms 63788 KB Output is correct
3 Correct 77 ms 35360 KB Output is correct
4 Correct 188 ms 51656 KB Output is correct
5 Runtime error 500 ms 194748 KB Execution killed with signal 11
6 Halted 0 ms 0 KB -