Submission #697916

#	Time	Username	Problem	Language	Result	Execution time	Memory
697916		bLIC	Valley (BOI19_valley)	C++17	100 / 100	230 ms	52132 KiB

valley

/**
 *  Author: Anil Byar
**/

#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>

// using namespace __gnu_pbds;
using namespace std;

// template<class T>
// using ordered_set = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;



#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)(x).size()
#define ft first
#define sd second
#define pb push_back

// Source: https://codeforces.com/blog/entry/68809
// { start
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '"' << x << '"';}
void __print(const string &x) {cerr << '"' << x << '"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
// } end


typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<pll> vll;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
typedef vector<vl> vvl;

#define dbg if(0)

const ll MOD = 1e9+7;
const ll INFLL = 1e18+5;
const int INF = 1e9;
const int maxN = 1e5+5;
const int maxK = 18;

void printbit(int x, int len) {string s="\n";while(len--){s=((x%2)?'1':'0')+s;x/=2;} cout<<s;}

template<class T>
istream& operator>>(istream&in, vector<T>&v){
    for (T& x:v) in>>x;
    return in;
}
template<class T>
ostream& operator<<(ostream&out, vector<T>&v){
    for (T& x:v) out<<x<<' ';
    cout<<'\n';
    return out;
}

vii adj[maxN];
int dep[maxN];
int par[maxN][maxK];
ll dist[maxN][maxK];
bool shop[maxN];
ll mnshop[maxN];
ll mnshopup[maxN][maxK];

void dfs(int node, int p = -1){
    if (shop[node]) mnshop[node] = 0;

    for (auto x:adj[node]){
        int v = x.ft, w = x.sd;
        if (v==p) continue;
        par[v][0] = node;
        dist[v][0] = w;
        dep[v] = dep[node] + 1;
        dfs(v, node);
        mnshop[node] = min(mnshop[node], mnshop[v]+w);
    }
}

int kup(int x, int k){
    for (int i = 0;i<maxK;i++){
        if ((k>>i)&1) x = par[x][i];
    }
    return x;
}

ll getbest(int from, int up){
    ll d = 0;
    ll ans = mnshop[from];
    for (int i = 0;i<maxK;i++){
        if (up>>i&1){
            ans = min(ans, d+mnshopup[from][i]);
            d += dist[from][i];
            from = par[from][i];
        }
    }
    return ans;
}

void solve(){
    // ll x = 0;
    // memset(&x, 127, sizeof(x));
    // cout<<x;
    int n, s, q, e;
    cin>>n>>s>>q>>e;
    vii edges(n);
    for (int i = 1;i<n;i++){
        int u, v, w;cin>>u>>v>>w;
        edges[i] = {u, v};
        adj[u].emplace_back(v, w);
        adj[v].emplace_back(u, w);
    }
    for (int i = 0;i<s;i++){
        int x;cin>>x;
        shop[x] = 1;
    }
    for (int i = 0;i<=n;i++){
        for (int j = 0;j<maxK;j++) {
            dist[i][j] = INFLL;
            mnshopup[i][j] = INFLL;
            mnshop[i] = INFLL;
        }
    }
    // memset(dist, 127, sizeof(dist));
    // memset(mnshop, 127, sizeof(mnshop));
    // memset(mnshopup, 127, sizeof(mnshopup));
    dfs(e);
    for (int i = 1;i<=n;i++){
        mnshopup[i][0] = min(mnshop[i], mnshop[par[i][0]] + dist[i][0]);
    }
    for (int i = 1;i<maxK;i++){
        for (int j = 1;j<=n;j++){
            par[j][i] = par[par[j][i-1]][i-1];
            dist[j][i] = dist[par[j][i-1]][i-1] + dist[j][i-1];
            mnshopup[j][i] = min(mnshopup[j][i-1], mnshopup[par[j][i-1]][i-1] + dist[j][i-1]);
        }
    }

    while(q--){
        int i, r;cin>>i>>r;
        int v = (dep[edges[i].ft]<dep[edges[i].sd]?edges[i].sd:edges[i].ft);
        if (dep[v]>dep[r] || kup(r, dep[r]-dep[v])!=v) { // is v ancestor of r// can also be checked by st < st and en > en
            cout<<"escaped\n";
        }else {
            int up = dep[r]-dep[v];
            ll ans = getbest(r, up);
            if (ans!=INFLL) cout<<ans<<'\n';
            else cout<<"oo\n";
        }
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

// #define _DEBUG
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.out", "w", stdout);
    int tt = clock();
#endif

    int t=1, i = 1;
    // cin>>t;
    while(t--){
        // cout<<"Case #"<<i++<<": ";
        solve();
        cout<<'\n';
    }
#ifdef _DEBUG
    cerr << "TIME = " << (float)(clock() - tt)/CLOCKS_PER_SEC << endl;
    tt = clock();
#endif
}

Compilation message (stderr)

valley.cpp: In function 'int main()':
valley.cpp:195:14: warning: unused variable 'i' [-Wunused-variable]
  195 |     int t=1, i = 1;
      |              ^

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