Submission #1081814

#	Time	Username	Problem	Language	Result	Execution time	Memory
1081814		Tymond	Event Hopping (BOI22_events)	C++17	20 / 100	99 ms	12996 KiB

events

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::steady_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

const int MAXN = 1e5 + 7;
const int BASE = (1 << 17);
const int MAXK = 20;
int pos[MAXN];
pii tree[2 * BASE + 7];
int range[MAXK][MAXN];
vector<pair<pii, int>> vec;
int n, q;

pii smaller(pii x, pii y){
    if(x.fi != y.fi){
        return (x.fi < y.fi ? x : y);
    }
    return (x.se < y.se ? x : y);
}

void upd(int ind, pii val){
    ind += BASE;
    tree[ind] = val;
    ind /= 2;
    while(ind > 0){
        tree[ind] = smaller(tree[2 * ind], tree[2 * ind + 1]);
        ind /= 2;
    }
}

pii query(int v, int l, int p, int a, int b){
    if(p < a || b < l){
        return {1e9, 1e9};
    }

    if(a <= l && p <= b){
        return tree[v];
    }
    int mid = (l + p) / 2;
    return smaller(query(2 * v, l, mid, a, b), query(2 * v + 1, mid + 1, p, a, b));
}

void preprocessing(){
    for(int i = 0; i < 2 * BASE + 7; i++){
        tree[i] = {1e9, 1e9};
    }

    for(int i = 0; i < n; i++){
        upd(i, {vec[i].fi.fi , i});
    }
   // cout << "RANGES\n";
    for(int i = 0; i < n; i++){
        int l = 0;
        int p = i;
        int s;
        while(l < p){
            s = (l + p) / 2;
            if(vec[s].fi.se < vec[i].fi.fi){
                l = s + 1;
            }else{
                p = s;
            }
        }
      //  cout << i << ' ' << l << ' ';
        range[0][i] = query(1, 0, BASE - 1, l, i).se;
       // cout << range[0][i] << '\n';
    }

    for(int k = 1; k < MAXK; k++){
        for(int i = 0; i < n; i++){
            range[k][i] = range[k - 1][range[k - 1][i]];
        }
    }
}

int solve(int a, int b){
    if(vec[a].fi.se >= vec[b].fi.fi && vec[a].fi.se <= vec[b].fi.se){
        return 1;
    }
    
    int res = 0;
    int akt = b;
    for(int i = MAXK - 1; i >= 0; i--){
        int nr = range[i][akt];
        if(nr == akt){
            break;
        }
        if(vec[a].fi.se >= vec[nr].fi.se){
            continue;
        }
        res += (1 << i);
        akt = nr;
        if(vec[a].fi.se >= vec[akt].fi.fi && vec[a].fi.se <= vec[akt].fi.se){
            return res + 1;
        }
    }

    return -1;
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    cin >> n >> q;
    for(int i = 1; i <= n; i++){
        int s,e;
        cin >> s >> e;
        vec.pb({{e, s}, i});
    }

    sort(all(vec));
    for(int i = 0; i < n; i++){
        swap(vec[i].fi.fi, vec[i].fi.se);
        pos[vec[i].se] = i;
    }

    preprocessing();

    /*for(auto ele : vec){
        cout << ele.fi.fi << ' ' << ele.fi.se << '\n';
    }

    for(int i = 0; i < n; i++){
        for(int j = 0; j < MAXK / 2; j++){
            cout << range[j][i] << ' ';
        }
        cout << '\n';
    }*/

    while(q--){
        int s, e;
        cin >> s >> e;
        s = pos[s];
        e = pos[e];
       // cout << "PYTANIE: " << s << ' ' << e << '\n';
        if(s == e){
            cout << 0 << '\n';
            continue;
        }

        int ans = solve(s, e);
        if(ans == -1){
            cout << "impossible\n";
        }else{
            cout << ans << '\n';
        }
    }

    return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 20 / 20
• Subtask 6: 0 / 30