Submission #490609

#	Time	Username	Problem	Language	Result	Execution time	Memory
490609		Carmel_Ab1	Valley (BOI19_valley)	C++17	100 / 100	413 ms	54548 KiB

valley

#include<bits/stdc++.h>
#pragma GCC optimize ("Ofast")
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>

//using namespace __gnu_pbds;
using namespace std;

typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef vector<pl> vpl;
typedef vector<ld> vld;
typedef pair<ld, ld> pld;
typedef vector<pi> vpi;

//typedef tree<ll, null_type, less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
template<typename T>
ostream &operator<<(ostream &os, vector<T> &a) {
    os << "[";
    for (int i = 0; i < ll(a.size()); i++) { os << a[i] << ((i != ll(a.size() - 1) ? " " : "")); }
    os << "]\n";
    return os;
}

#define all(x) x.begin(),x.end()
#define YES out("YES")
#define NO out("NO")
#define out(x){cout << x << "\n"; return;}
#define GLHF ios_base::sync_with_stdio(false); cin.tie(NULL);cout.tie(NULL)
#define print(x){for(auto ait:x) cout << ait << " "; cout << "\n";}
#define pb push_back
#define umap unordered_map

template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
    is >> p.first >> p.second;
    return is;
}

template<typename T1, typename T2>
ostream &operator<<(ostream &os, pair<T1, T2> &p) {
    os << "" << p.first << " " << p.second << "";
    return os;
}

void usaco(string taskname) {
    string fin = taskname + ".in";
    string fout = taskname + ".out";
    const char *FIN = fin.c_str();
    const char *FOUT = fout.c_str();
    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);
}

template<typename T>
void read(vector<T> &v) {
    int n = v.size();
    for (int i = 0; i < n; i++)
        cin >> v[i];
}

template<typename T>
vector<T> UNQ(vector<T> a) {
    vector<T> ans;
    for (T t: a)
        if (ans.empty() || t != ans.back())
            ans.push_back(t);
    return ans;
}

ll ceil(ll a, ll b) {
    ll ans = a / b;
    if (a % b)ans++;
    return ans;
}

ld log(ld a, ld b) { return log(b) / log(a); }

ll power(ll base, ll exp, ll M = 1e18) {//(base^exp)%M
    ll ans = 1;
    while (exp) {
        if (exp % 2 == 1)ans = ((ans % M) * (base % M)) % M;
        base = ((base % M) * (base % M)) % M;
        exp /= 2;
    }
    return ans;
}

string to_base(int n, int new_base) {
    string s;
    int nn = n;
    while (nn) {
        s += to_string(nn % new_base);
        nn /= new_base;
    }
    reverse(all(s));
    return s;
}

ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;
    return gcd(b, a % b);
}

ll lcm(ll a, ll b) {
    ll x = (a / gcd(a, b));
    return b * x;
}

vl generate_array(ll n, ll mn = 1, ll mx = 1e18 + 1) {
    if (mx == 1e18 + 1)
        mx = n;
    vl ans(n);
    for (int i = 0; i < n; i++)
        ans[i] = (mn + rand() % (mx - mn + 1));
    return ans;
}

string substr(string s, int l, int r) {
    string ans;
    for (int i = l; i <= r; i++)
        ans += s[i];
    return ans;
}


void solve();

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

vl a;
vector<vpl> g;
vvl E;
vvi up;
vvl mn;
vi tin,tout,dep;
vl down,dist;

int timer=0,lg=20;
int n, s, q, e;

void dfs(int src,int par){
    tin[src]=++timer;
    if(par!=-1)
        dep[src]=dep[par]+1;
    up[src][0]=par;
    if(a[src])
        down[src]=0;

    for(pi nbr:g[src])
        if(nbr.first!=par) {
            dist[nbr.first]=dist[src]+nbr.second;
            dfs(nbr.first, src);
            down[src]=min(down[src],down[nbr.first]+nbr.second);
        }
    mn[src][0]=down[src]-dist[src];

    tout[src]=timer;
}


ll calc(int r,int u,int v){
    // u is lower
    ll ans=1e18;

    int p=r;
    for(int i=0; i<lg; i++)
        if((dep[p]-dep[v])&(1<<i)){
            ans=min(ans,dist[r]+mn[p][i]);
            p=up[p][i];
        }


    return ans;
}

void solve() {
    cin >> n >> s >> q >> e;

    g.resize(n + 1);

    for(int i=0; i<n-1; i++){
        ll u,v,w;
        cin >> u >> v >> w;
        g[u].pb({v,w});
        g[v].pb({u,w});
        E.pb({u,v,w});
    }

    a.resize(n+1);

    for(int i=0; i<s; i++){
        int x;
        cin >> x;
        a[x]=1;
    }
    tin.resize(n+1);
    tout.resize(n+1);
    dep.resize(n+1);
    down.resize(n+1,1e18);
    dist.resize(n+1);
    up.resize(n+1,vi(lg,-1));
    mn.resize(n+1,vl(lg,1e18));

    dfs(e,-1);

    for(int j=1; j<lg; j++)
        for(int i=1; i<=n; i++){
            if(up[i][j-1]==-1)
                continue;
            up[i][j]=up[up[i][j-1]][j-1];
            mn[i][j]=min(mn[i][j-1],mn[up[i][j-1]][j-1]);
        }

    while(q--){
        int i,r;
        cin >> i >> r;
        int u=E[i-1][0],v=E[i-1][1];
        if(dep[u]<dep[v])
            swap(u,v);
        //u is lower

        if(!(tin[u]<=tin[r] && tout[r]<=tout[u])){
            cout << "escaped" << endl;
            continue;
        }
        if(s==n){
            cout << "0" << endl;
            continue;
        }
        ll ans=calc(r,u,v);
        if(ans==1e18)
            cout << "oo" << endl;
        else
            cout << ans << endl;
    }
}

Compilation message (stderr)

valley.cpp: In function 'void usaco(std::string)':
valley.cpp:58:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   58 |     freopen(FIN, "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~
valley.cpp:59:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |     freopen(FOUT, "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~

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