Submission #258729

#	Time	Username	Problem	Language	Result	Execution time	Memory
258729		anubhavdhar	Valley (BOI19_valley)	C++14	0 / 100	563 ms	38052 KiB

valley

#include<bits/stdc++.h>

#define ll long long
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define pll pair<ll, ll>
#define ff first 
#define ss second
#define vi vector<int>
#define vl vector<ll>
#define vii vector<pii>
#define vll vector<pll>
#define FOR(i,N) for(i=0;i<(N);++i)
#define FORe(i,N) for(i=1;i<=(N);++i)
#define FORr(i,a,b) for(i=(a);i<(b);++i)
#define FORrev(i,N) for(i=(N);i>=0;--i)
#define F0R(i,N) for(int i=0;i<(N);++i)
#define F0Re(i,N) for(int i=1;i<=(N);++i)
#define F0Rr(i,a,b) for(ll i=(a);i<(b);++i)
#define F0Rrev(i,N) for(int i=(N);i>=0;--i)
#define all(v) (v).begin(),(v).end()
#define dbgLine cerr<<" LINE : "<<__LINE__<<"\n"
#define ldd long double

using namespace std;

const int Alp = 26;
const int __PRECISION = 9;
const int inf = 1e9 + 8;

const ldd PI = acos(-1);
const ldd EPS = 1e-7;

const ll MOD = 1e9 + 7;
const ll MAXN = 1e5 + 5;
const ll ROOTN = 320;
const ll LOGN = 18;
const ll INF = 1e18 + 1022;

int N, Q, E, S, CLK, xt[MAXN], nt[MAXN], par[LOGN][MAXN], depcnt[MAXN];
ll dp[MAXN], sparse[LOGN][MAXN], dep[MAXN];
bool shop[MAXN];
vector<pair<int, ll>> g[MAXN];
vector<pair<pii, ll>> edge_list;

ll dfs(int a, int pp)
{
	nt[a] = CLK++;
	par[0][a] = pp;
	for(pair<int, ll> b : g[a])
		if(b.ff != pp)
		{
			dep[b.ff] = b.ss + dep[a];
			depcnt[b.ff] = 1 + dep[a];
			dp[a] = min(dp[a], dfs(b.ff, a) + b.ss);
		}
	if(shop[a])
		dp[a] = 0;
	for(pair<int, ll> b : g[a])
		if(b.ff != pp)
		{
			// cerr<<"sparse[0]["<<b.ff<<"] = "<<min(sparse[0][b.ff], b.ss + dp[a])<<'\n';
			sparse[0][b.ff] = min(sparse[0][b.ff], b.ss + dp[a]);
		}
	xt[a] = CLK++;
	return dp[a];
}

inline void init_sparse_table()
{
	F0Re(i, LOGN-1)
		F0Re(a, N)
			par[i][a] = (par[i-1][a] == -1) ? -1 : par[i-1][par[i-1][a]],
			sparse[i][a] = min(sparse[i-1][a],(((par[i-1][a]==-1) ? INF : (sparse[i-1][par[i-1][a]] + dep[a] - dep[par[i-1][a]]))));
}

// inline void dbg_dp()
// {
// 	F0Re(i, N)
// 		cout<<"dp["<<i<<"] = "<<dp[i]<<'\n';
// }

inline void pre_process()
{
	CLK = 0;
	dep[E] = depcnt[E] = 0;
	F0Re(i, N)
		dp[i] = INF;
	F0R(i, LOGN)
		F0Re(a, N)
			sparse[i][a] = INF;
	dfs(E, -1);
	// dbg_dp();
	init_sparse_table();
}

inline void query(int e, int a)
{
	int u = (depcnt[edge_list[e].ff.ff] > depcnt[edge_list[e].ff.ss]) ? edge_list[e].ff.ff : edge_list[e].ff.ss;
	if(!(nt[u] <= nt[a] and xt[u] >= xt[a]))
	{
		cout<<"escaped\n";
		return;
	}
	int b = a;
	ll ans = dp[a];
	F0Rrev(i, LOGN-1)
	{
		if(par[i][b] == -1 or depcnt[par[i][b]] < depcnt[u])
			continue;
		ans = min(ans, sparse[i][b] + dep[a] - dep[b]);
		// cerr<<"considering "<<par[i][b]<<" and sparse["<<i<<"]["<<b<<"] = "<<sparse[i][b]<<'\n';
		b = par[i][b];
	}
	if(ans == INF)
		cout<<"oo\n";
	else
		cout<<ans<<'\n';
}

signed main()
{

	/*
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	*/
	int j, k;
	ll len;
	cin>>N>>S>>Q>>E;
	F0R(i, N-1)
	{
		cin>>j>>k>>len;
		edge_list.pb(mp(mp(j, k), len));
		g[j].pb(mp(k,len));
		g[k].pb(mp(j,len));
	}

	F0Re(i, N)
		shop[i] = false;
	
	F0Re(i, S)
	{
		cin>>j;
		shop[j] = true;
	}


	// F0Re(i, N)
	// 	cerr<<shop[i]<<' ';
	// cerr<<'\n';

	pre_process();

	while(Q--)
	{
		cin>>j>>k;
		query(j-1, k);
	}	

	return 0;
}
/*
5 2 3 1 
1 2 3
1 3 2
3 4 1 
3 5 2 
2 4 
2 2 
2 5
4 5 

10 2 5 4
7 2 3
4 8 3
9 10 1
6 7 3
9 2 3
10 1 2
8 2 2
5 2 1
3 8 2
8
7
2 1
1 5
8 4
6 2
7 7

*/

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