Submission #1259460

#	Time	Username	Problem	Language	Result	Execution time	Memory
1259460		tnt	Valley (BOI19_valley)	C++20	0 / 100	80 ms	46772 KiB

valley

#include <bits/stdc++.h>
using namespace std;
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("Ofast,unroll-loops,fast-math,O3")
 

#define pb push_back                    
#define ll long long
#define int long long  
//#define sz(v) int(v.size())
#define all(v) v.begin(),v.end()
#define f first
#define s second
 
int mod =  998244353;
const long long inf = 1e18;
const int N = 1e5 + 10;
int dp[N],s[N],dist[N],pr[N];
vector <pair <int,int>> g[N];
int up[N][20],up1[N][20];
int tin[N],tout[N],depth[N];
int timer = 0;
void dfs(int u,int p){
	if(s[u] == 1) dp[u] = 0;
	else dp[u] = inf;
	pr[u] = p,tin[u] = ++timer;
	for(auto [to,w] : g[u]){
		if(to == p) continue;
		dist[to] = dist[u] + w,depth[to] = depth[u] + 1;
		dfs(to,u);
		dp[u] = min(dp[to] + w,dp[u]);
	}
	tout[u] = timer;
}
void dfs1(int u,int p){
	up[u][0] = p,up1[u][0] = min(dp[p] - dist[p],dp[u] -  dist[u]);
	for(int i = 1; i < 20; i++) up[u][i] = up[up[u][i - 1]][i - 1];
	for(int i = 1; i < 20; i++) up1[u][i] = min(up1[up[u][i - 1]][i - 1],up1[u][i - 1]);
	for(auto [to,w] : g[u]){
		if(to == p) continue;
		dfs1(to,u);
	}
}
void solve(){                    
    int n,m,q,x;
    cin >> n >> m >> q >> x;
    vector <pair <int,int>> qr;
    for(int i = 2; i <= n; i++){
    	int u,v,w;
    	cin >> u >> v >> w;
    	g[u].pb({v,w}),g[v].pb({u,w});
    	qr.pb({u,v});	
    }
    for(int i = 1; i <= m; i++){
    	int u;
    	cin >> u;
    	s[u] = 1;
    }
    dfs(x,x),dfs1(x,x);
    while(q--){
    	int i,d;
    	cin >>i >> d;
    	int u = qr[i - 1].f,v = qr[i - 1].s;
    	if(pr[u] == v) swap(u,v);
    	if(tin[v] <= tin[d] && tout[d] <= tout[v]){
    		int ans = inf,dist1 = depth[d] - depth[v],f = dist[d];
    		for(int i = 0; i < 20; i++){
    			if((dist1 >> i & 1) == 1){
    				ans = min(ans,up1[d][i]); 
    				d = up[d][i];
    			}
    		}                                                   
    		if(ans + f >= 1e15) cout << "oo\n";
    		else cout << ans + f << '\n';
    	}
    	else{
    		cout << "escaped\n";	
    	}
    }
    
}
signed main(){
    //freopen("floor4.in", "r", stdin);
    //freopen("floor4.out", "w", stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    int t = 1;
    while(t--){
    	solve();
    }
}

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