Submission #931273

#	Time	Username	Problem	Language	Result	Execution time	Memory
931273		penguin133	Firefighting (NOI20_firefighting)	C++17	22 / 100	235 ms	46128 KiB

Firefighting

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

pi dp[300005]; // no of stuff, max dist of a node not alr covered by fire
int md[300005], dep[300005];
int n, k;
vector <pi> adj[300005];
vector <int> ans;

void dfs(int x, int par, int w, int cur){
	dep[x] = cur;
	md[x] = 1e18;
	int mx = -1e18;
	for(auto [i, j] : adj[x]){
		if(i == par)continue;
		dfs(i, x, j, cur + j);
		md[x] = min(md[x], md[i]);
		dp[x].fi += dp[i].fi;
		mx = max(mx, dp[i].se + j);
	}
	int tmp = md[x] - dep[x];
	if(tmp > k)mx = max(mx, 0ll);
	dp[x].se = mx;
	if(mx + w > k && mx >= 0){
		ans.push_back(x);
		md[x] = dep[x];
		dp[x].fi++;
		dp[x].se = -1e18;
	}
}

void solve(){
	cin >> n >> k;
	for(int i = 1; i < n; i++){
		int a, b, c; cin >> a >> b >> c;
		adj[a].push_back({b, c}); adj[b].push_back({a, c});
	}
	dfs(1, -1, 1e18, 0);
	cout << (int)ans.size() << '\n';
	for(auto i : ans)cout << i << ' ';
}

main(){
	ios::sync_with_stdio(0);cin.tie(0);
	int tc = 1;
	//cin >> tc;
	for(int tc1=1;tc1<=tc;tc1++){
		// cout << "Case #" << tc1 << ": ";
		solve();
	}
}

Compilation message (stderr)

Firefighting.cpp:53:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   53 | main(){
      | ^~~~

• Subtask 1: 3 / 3
• Subtask 2: 0 / 5
• Subtask 3: 0 / 9
• Subtask 4: 19 / 19
• Subtask 5: 0 / 26
• Subtask 6: 0 / 38