Submission #328633

#	Time	Username	Problem	Language	Result	Execution time	Memory
328633		soroush	Valley (BOI19_valley)	C++14	100 / 100	314 ms	66796 KiB

valley

//*
#pragma GCC optimize("O2")
//#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC target("avx,avx2,sse,sse2,fma,tune=native")
//*/
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll  ,ll > pii;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const ll maxn  = 1e5 + 100;
const ll mod =1e9+7;
const ld PI = acos((ld)-1);

#define pb push_back
#define endl '\n'
#define dokme(x) cout << x , exit(0)
#define migmig ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define ms(x , y) memset(x , y , sizeof x)
ll pw(ll a, ll b, ll md = mod){ll res = 1;while(b){if(b&1){res=(a*res)%md;}a=(a*a)%md;b>>=1;}return(res);}

int n , q , s , ex;
bool shop[maxn];

pii e[maxn];
ll w[maxn];

int par[maxn][23];
vector < pii > adj[maxn];
int h[maxn];
int l[maxn] , r[maxn] , t = 0;
ll H[maxn];
int ord[maxn];

void dfs(int v){
	r[v] = l[v] = ++t;
	ord[t] = v;
    for (auto uw : adj[v]){
		auto u = uw.first;
		auto w = uw.second;
        if(u!=par[v][0]){
            par[u][0] = v;
            h[u] = h[v]+1;
            H[u] = H[v] + w;
            dfs(u);
            r[v] = r[u];
        }
	}
}

int lca(int u , int v){
    if(h[u] > h[v]){
        swap(u , v);
    }
    for (int i = 20 ; i >= 0 ; i --){
        if(par[v][i] and h[par[v][i]]>=h[u]){
            v = par[v][i];
        }
    }
    if(v == u){
        return(v);
    }
    for (int i = 20 ; i >= 0 ; i --){
        if(par[v][i] != par[u][i]){
            v = par[v][i] , u = par[u][i];
        }
    }
    return(par[v][0]);
}

void init(){
	dfs(ex);
    for (int j = 1; j <= 20 ; j ++){
        for (int i = 1 ; i <= n ; i ++){
            par[i][j] = par[par[i][j - 1]][j - 1];
        }
    }
}

ll dist(int u , int v){
	return(H[u] + H[v] - 2*H[lca(u, v)]);
}

ll f[maxn][23];
ll val[maxn][23];

ll mn(ll l , ll r){
	ll cur = l;
	ll ans = val[l][0];
	for(int i = 20 ; i >= 0 ; i --){
		if(cur + (1 << i) > r)continue;
		ans = min(ans , val[cur][i]);
		cur+=(1 << i);
		ans = min(ans , val[cur][0]);
	}
	return(ans);
}

int32_t main(){
    migmig;
	cin >> n >> s >> q >> ex;
	for(int i = 1 ; i < n ; i ++)
		cin >> e[i].first >> e[i].second >> w[i],
		adj[e[i].first].pb({e[i].second , w[i]}),
		adj[e[i].second].pb({e[i].first , w[i]});
	for(int i = 0 ; i < s ; i ++){
		int x;
		cin >> x;
		shop[x] = 1;
	}
	init();
	h[0] = -1;
	for(int i = 1 ; i <= n ; i ++){
		if(shop[i])val[l[i]][0] = H[i];
		else val[l[i]][0] = 1e18;
	}
	for(int j = 0 ; j < 20 ; j ++){
		for(int i = 1 ; i <= n ; i ++){
			if(i + (1 << j) > n)continue;
			val[i][j+1] = min(val[i][j] , val[i + (1 << j)][j]);
		}
	}
	for(int i = 1 ; i <= n ; i ++){
		if(mn(l[i] , r[i]) == 1e18)
			f[i][0] = 1e18;
		else
			f[i][0] = mn(l[i] , r[i]) - 2LL*H[i];
	}
	for(int j = 1 ; j <= 20 ; j ++)
		for(int i = 1 ; i <= n ; i ++)
			f[i][j] = min(f[i][j-1] ,f[par[i][j-1]][j-1]);
	while(q -- ){
		int i , V;
		cin >> i >> V;
		auto u = e[i].first;
		auto v = e[i].second;
		if(h[u] < h[v])swap(u , v);
		if(l[u] <= l[V] and l[V] <= r[u]){
			if(f[u][0] == 1e18){
				cout << "oo" << endl;
			}
			else{
				int cur = V;
				ll ans = 1e18;
				for(int i = 20 ; i >= 0 ; i --){
					if(h[par[cur][i]] < h[u] )continue;
					ans = min(ans , f[cur][i]);
					cur = par[cur][i];
					ans = min(ans , f[cur][0]);
				}
				ans = min(ans , f[cur][0]);
				cout << ans + H[V] << endl;
			}
		}
		else{
			cout << "escaped" << endl;
		}
	}
    return(0);
}

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