Submission #496275

#	Time	Username	Problem	Language	Result	Execution time	Memory
496275		Nalrimet	Valley (BOI19_valley)	C++17	36 / 100	3067 ms	18512 KiB

valley

//#pragma GCC target("avx2")
//#pragma GCC optimization("O3")
//#pragma GCC optimization("unroll-loops")
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>

#define ll long long
#define pb push_back
#define F first
#define S second

using namespace std;

const int N = 2 * 1e5 + 5;
const int MOD = 1e9 + 7;
const int K = 18;
const long long inf = 1e18;

int n, m, h[N], q, a[N], b[N], t[N], r[N], parent[N], par[N][K], s, e, x[N], son;
vector<pair<int, int>> g[N];
long long d[N];

void dfs(int v, int pr){
	par[v][0] = pr;

	for(auto to : g[v]){
		if(to.F != pr){
			d[to.F] = d[v] + to.S;
			h[to.F] = h[v] + 1;
			dfs(to.F, v);
		}
	}
}

bool bit(int x, int p){
	return x & (1 << p);
}

int lift(int v, int k){
	for(int i = 0; i < K; i++){
		if (bit(k, i)) {
			v = par[v][i];
		}
	}
	return v;
}

int lca(int a, int b){
	if(h[a] < h[b]){
		swap(a, b);
	}
	a = lift(a, h[a] - h[b]);
	if(a == b){
		return a;
	}
	for(int i = K - 1; i >= 0; --i){
		if(par[a][i] != par[b][i]){
			a = par[a][i];
			b = par[b][i];
		}
	}
	return par[a][0];
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

	cin >> n >> s >> q >> e;

	for(int i = 1, u, v, w; i < n; i++){
		cin >> u >> v >> w;
		g[u].pb({v, w});
		g[v].pb({u, w});
		a[i] = u;
		b[i] = v;
	}

    dfs(1, 1);

    for(int i = 1; i < K; i++){
    	for(int v = 1; v <= n; v++){
    		par[v][i] = par[par[v][i - 1]][i - 1];
    	}
    }

    for(int i = 1; i <= s; ++i){
        cin >> x[i];
    }

    for(int i = 1; i <= q; ++i){
        cin >> t[i] >> r[i];
        if(par[a[t[i]]][0] == b[t[i]]) son = a[t[i]];
        else son = b[t[i]];
        if(lca(son, r[i]) == son){
            if(lca(son, e) == son) {cout << "escaped\n"; continue;}
            else {
                ll res = inf;
                for(int j = 1; j <= s; ++j){
                    if(lca(x[j], son) == son){
                        res = min(res, d[x[j]] + d[r[i]] - d[lca(r[i], x[j])] * 2);
                    }
                }
                if(res == inf) cout << "oo\n";
                else cout << res << '\n';
            }
        }
        else{
            if(lca(son, e) != son) {cout << "escaped\n"; continue;}
            else{
                ll res = inf;
                for(int j = 1; j <= s; ++j){
                    if(lca(x[j], son) != son){
                        res = min(res, d[x[j]] + d[r[i]] - d[lca(r[i], x[j])] * 2);
                    }
                }
                if(res == inf) cout << "oo\n";
                else cout << res << '\n';
            }
        }
    }

	return 0;
}

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