Submission #547665

#	Time	Username	Problem	Language	Result	Execution time	Memory
547665		Soul234	Valley (BOI19_valley)	C++14	100 / 100	203 ms	37060 KiB

valley

#include<bits/stdc++.h>
using namespace std;

void DBG() { cerr << "]\n"; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << h; if(sizeof...(t)) cerr << ", ";
    DBG(t...);
}
#ifdef LOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif // LOCAL

#define FOR(i,a,b) for(int i = (a) ; i<(b) ; i++)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for(int i = (b)-1 ; i>=(a) ; i--)
#define R0F(i,a) ROF(i,0,a)
#define each(e,a) for(auto &e : (a))
#define sz(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pb push_back
#define tcT template<class T
#define nl "\n"

using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
using str = string;
tcT> using V = vector<T>;
tcT> using pqg = priority_queue<T,vector<T>,greater<T>>;

void setIO(string NAME = "") {
    cin.tie(0)->sync_with_stdio(0);
    if(sz(NAME)) {
        freopen((NAME + ".inp").c_str(),"r",stdin);
        freopen((NAME + ".out").c_str(),"w",stdout);
    }
}

#define f first
#define s second

tcT> bool ckmin(T&a, const T&b) {
    return b < a ? a = b, 1 : 0;
}
const int MX = 1e5+5, LG = 17;
const ll INF = 1e18;
int N, S, Q, E, jmp[MX][LG], tin[MX], tout[MX], timer_;
ll dp[MX], mnjmp[MX][LG], dep[MX];
pi eds[MX];
V<pi> adj[MX];

void dfs(int u, int p) {
    tin[u] = ++timer_;
    if(dp[u] == -1) dp[u] = dep[u];
    each(v, adj[u]) if(v.f != p) {
        dep[v.f] = dep[u] + v.s;
        dfs(v.f, u);
        ckmin(dp[u], dp[v.f]);
    }
    tout[u] = timer_;
}

void DFS(int u, int p) {
    mnjmp[u][0] = min(dp[u], dp[p]);
    FOR(i,1,LG) {
        jmp[u][i] = jmp[jmp[u][i-1]][i-1];
        mnjmp[u][i] = min(mnjmp[u][i-1], mnjmp[jmp[u][i-1]][i-1]);
    }
    each(v, adj[u]) if(v.f != p) {
        jmp[v.f][0] = u;
        DFS(v.f, u);
    }
}

bool isa(int u, int v) { return tin[u] <= tin[v] && tout[v] <= tout[u]; }

void solve() {
    cin>>N>>S>>Q>>E;
    memset(dp, 0x3f, sizeof dp);
    memset(mnjmp, 0x3f, sizeof mnjmp);
    F0R(_,N-1) {
        int u,v,w;
        cin>>u>>v>>w;
        adj[u].pb({v,w});
        adj[v].pb({u,w});
        eds[_+1] = {u,v};
    }
    F0R(i,S) {
        int x; cin>>x;
        dp[x] = -1;
    }
    //dbg(N);
    dfs(E, -1);
    FOR(i,1,N+1) dp[i] -= 2*dep[i];
    jmp[E][0] = E;
    DFS(E,E);
    //dbg(dp[3]);
    while(Q-->0) {
        int I, R; cin>>I>>R;
        int x = eds[I].f, y = eds[I].s;
        if(dep[x] > dep[y]) swap(x,y);
        if(isa(y, R)) {
            ll ans = dp[R];
            int cur = R;
            R0F(i,LG) if(isa(y,jmp[R][i])) ckmin(ans, mnjmp[R][i]), R = jmp[R][i];
            if(ans>=INF) {
                cout << "oo\n";
                continue;
            }
            cout << ans + dep[cur] << nl;
        }
        else {
            cout << "escaped\n";
        }
    }
}

int main() {
    setIO();

    int t=1;
    //cin>>t;
    while(t-->0) {
        solve();
    }

    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'void setIO(std::string)':
valley.cpp:37:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         freopen((NAME + ".inp").c_str(),"r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
valley.cpp:38:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |         freopen((NAME + ".out").c_str(),"w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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