Submission #700030

#	Time	Username	Problem	Language	Result	Execution time	Memory
700030		arashMLG	Valley (BOI19_valley)	C++17	100 / 100	244 ms	56196 KiB

valley

#include<bits/stdc++.h>
#ifdef LOCAL
#include "Essentials/algo/debug.h"
#else
#define debug(...) 42
#endif
using namespace std;

typedef long long     ll;
typedef long double   ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll>   pll;

const int N = 1e5 + 18;
const ll mod = 1e9+7;
const int LOG = 23;
const ll inf = 1e18;

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

#define F           first
#define S           second
#define pb          push_back
#define ms(x,y)     memset((x) , (y) , sizeof (x))
#define done        return cout<<endl , 0;
#define kill(x)     cout<<x<<endl, exit(0);
#define isIn(x,s,e) ((x) >= (s) && (x) <= e)
#define all(x)      x.begin(),x.end()
#define sz(x)       (int)x.size()
#define pc(x)       __builtin_popcount(x)
#define ctz(x)      __builtin_ctz(x)
#define MinHeap(x)  priority_queue<x, vector<x> , greater<x> >
#define MaxHeap(x)  priority_queue<x, vector<x>>
#define int      ll

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,s,q,ex;
vector<pair<pll,int>> G[N];
int dp[N],up[N][LOG],dpup[N][LOG],dist[N];
int st[N],ft[N];
bool isShop[N];
pll edges[N];
int timer = 1;

void dfs(int v,int p = -1,int edge = -1) {
    st[v] = timer ++;
    if(isShop[v]) {
        dp[v] = dist[v];
    } else {
        dp[v] = inf; 
    }
    if(edge != -1) {
        edges[edge] = make_pair(v,p);
    }
    for(auto [e,id] : G[v]) {
        auto [u,w] = e;
        if(u == p) continue;
        dist[u] = dist[v] + w;
        up[u][0] = v;
        dfs(u,v,id);
        dp[v] = min(dp[v],dp[u]);
    }
    ft[v] = timer++;
}

int query(int v,int par) {
    int ans = inf;
    for(int i = LOG -1; i >= 0 ; i-- ) {
        int u = up[v][i];
        if(st[par] <= st[u] && ft[par] >= ft[u]) {
            debug(u,dpup[v][i]);
            ans= min(ans,dpup[v][i]);
            v = u;
        }
    }
    return ans;
}

int32_t main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    cin>>n>>s>>q>>ex;
    for(int i = 1; i <= n-1; i ++) {
        int v,u,w; cin>>v>>u>>w;
        G[v].pb({{u,w},i}); G[u].pb({{v,w},i});
    }
    for(int i = 1; i <= s; i ++) {int v; cin>>v; isShop[v] = true;}
    dfs(ex);
    for(int v = 1; v<= n; v ++) {
        if(dp[v] != inf) {
            dp[v] -= 2 * dist[v];
        }
        dpup[v][0] = dp[v];
    }
    for(int i = 1; i < LOG; i ++) {
        for(int v = 1 ; v <= n; v++) {
            up[v][i] = up[up[v][i-1]][i-1];
            dpup[v][i] = min(dpup[v][i-1] , dpup[up[v][i-1]][i-1]);
        }
    }
    while(q--) {
        int I,r; cin>>I>>r;
        auto [p,pp] = edges[I];
        if(!(st[p] <= st[r] && ft[p] >= ft[r])) {
            cout<<"escaped\n";
        } else {
            int ans = query(r,pp);
            if(ans == inf) 
                cout<<"oo\n";
            else
                cout<<ans + dist[r]<<'\n';
        }  
    }
    done;
}

Compilation message (stderr)

valley.cpp: In function 'll query(ll, ll)':
valley.cpp:5:20: warning: statement has no effect [-Wunused-value]
    5 | #define debug(...) 42
      |                    ^~
valley.cpp:72:13: note: in expansion of macro 'debug'
   72 |             debug(u,dpup[v][i]);
      |             ^~~~~

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