Submission #1129881

#	Time	Username	Problem	Language	Result	Execution time	Memory
1129881		Nurislam	Valley (BOI19_valley)	C++17	23 / 100	231 ms	55188 KiB

valley

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp> 
//#include <ext/pb_ds/tree_policy.hpp> 
  
using namespace std;
//using namespace __gnu_pbds; 
  
#define int long long
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define ff first
#define ss second
#define pb push_back
//#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 
//#define ordered_multiset tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>

template<class T, class U> inline bool chmin(T& a, const U& b) { if (a > b) { a = b; return true; } return false; }
template<class T, class U> inline bool chmax(T& a, const U& b) { if (a < b) { a = b; return true; } return false; }
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//#define rnd(l, r) uniform_int_distribution <int> (l, r)(rng)

const int inf  = 1e18;
void solve(){
	int n, s, q, e;
	cin >> n >> s >> q >> e;
	vector<vector<array<int,2>>> g(n+1);
	vector<array<int,2>> edg(n);
	for(int i = 0; i < n-1; i++){
		int u, v, c;
		cin >> u >> v >> c;
		edg[i+1] = {u, v};
		g[u].pb({v, c});
		g[v].pb({u, c});
	}
	vector<int> dp(n+1, inf), dis(n+1, 0);
	while(s--){
		int x;cin >> x;
		dp[x] = 0;
	}
	
	auto prec = [&](auto prec, int ps, int pr) -> void{
		for(auto[to, c]:g[ps]){
			if(to == pr)continue;
			dis[to] = dis[ps] + c;
			prec(prec, to, ps);
			dp[ps] = min(dp[ps], dp[to] + c);
		};
	};
	prec(prec, e,e);
	
	vector<int> tin(n+1), tout(n+1);
	vector<vector<int>> lc(22, vector<int> (n+1)), mn(22, vector<int> (n+1, inf));
	int tim = 1;
	auto dfs = [&](auto dfs, int ps, int pr) -> void{
		tin[ps] = tim++;	
		lc[0][ps] = pr;
		mn[0][ps] = dp[ps] - dis[ps];
		for(int i = 1; i < 22; i++){
			lc[i][ps] = lc[i-1][lc[i-1][ps]];
			mn[i][ps] = min(mn[i-1][ps], mn[i-1][lc[i-1][ps]]);
		}
		for(auto [to, c]: g[ps]){
			if(to == pr)continue;
			dfs(dfs, to, ps);
		}
		tout[ps] = tim++;
	};
	dfs(dfs,e,e);
	
	while(q--){
		int id, ps;
		cin >> id >> ps;
		auto [a, b] = edg[id];
		if(dis[a] < dis[b])swap(a, b);
		
		if(tin[a] <= tin[ps] && tout[ps] <= tout[a]){
			int ans = dp[ps], res = ps;
			for(int i = 20; i >= 0; i--){
				if(dis[lc[i][res]] >= dis[a]){
					res = lc[i][res];
					chmin(ans, mn[i][res] + dis[ps]);
				}
			}
			if(ans == inf)cout << "oo\n";
			else cout << ans << '\n';
		}else cout << "escaped\n";
		
	}
};

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);
    int tt = 1;
    //cin >> tt;
    while(tt--){
        solve();
    };
}

• Subtask 1: 0 / 9
• Subtask 2: 0 / 27
• Subtask 3: 23 / 23
• Subtask 4: 0 / 41