Submission #723330

#	Time	Username	Problem	Language	Result	Execution time	Memory
723330		Mr_Husanboy	Event Hopping (BOI22_events)	C++17	40 / 100	1575 ms	19940 KiB

events

#include<bits/stdc++.h>
using namespace std;
 
#define all(a) (a).begin(), (a).end()
template<typename T>
int len(T &a){
    return a.size();
}
using ll = long long;
const int inf = 1e9;
const ll infl = 1e18;
#define ff first
#define ss second
 
struct Sparse{
    vector<vector<pair<int,int>>> t;
    int n, logn;
    pair<int,int> join(pair<int,int> a, pair<int,int> b){
        return min(a, b);
    }
    auto build(vector<int> &a){
        n = len(a);
        logn = 32 - __builtin_clz(n);
        t.assign(n, vector<pair<int,int>> (logn, pair{inf, 0}));
        for(int i = 0; i < n; i ++){
            t[i][0] = {a[i], i};
        }
        for(int j = 1; j < logn; j ++){
            for(int i = 0; i + (1 << j) <= n; i ++){
                t[i][j] = join(t[i][j - 1], t[i + (1 << (j - 1))][j - 1]);
            }
        }
    }
    int get(int l, int r){
        if(l > r) return inf;
        int len = r - l + 1;
        len = 31 - __builtin_clz(len);
        return join(t[l][len], t[r - (1 << len) + 1][len]).ss;
    }
};
 
 
 
 
 
void solve(){
    int n, q; cin >> n >> q;
    vector<tuple<int,int,int>> e(n);
    vector<pair<int,int>> ev(n);
    for(int i = 0; i < n; i ++){
        auto &[r, l, id] = e[i];
        cin >> l >> r;
        ev[i] = {l, r};
        //l = -l;
        id = i; 
    }
    sort(all(e));
    Sparse t;
    vector<int> lef(n);
    vector<int> pos(n);
    for(int i = 0; i < n; i ++){
        auto [r, l, id] = e[i];
        //l = -l;
        lef[i] = l;
        pos[id] = i;
        //cout << r << ' ' << l << endl;
    }
    t.build(lef);
    //for(auto u : lef) cout << u << ' '; cout << endl;
    vector<int> g(n);
    iota(all(g), 0);
    for(int i = 0; i < n; i ++){
        auto [r, l, id] = e[i];
        //l = -l;
        int ch = lower_bound(all(e), tuple{l, -1, -1}) - e.begin();
        //ch --;
        //cout << i << ' ' << ch << endl;
        int mn = t.get(ch, i);
        auto [rr, ll, idd] = e[mn];
        g[id] = idd;
    }
 //   for(int i = 0; i < n; i ++) cout << i << ' ' << g[i] << endl;
    while(q --){
        int a, b; cin >> a >> b; a --; b --;
        if(a == b){cout << "0\n"; continue;}
        bool ok = 0;
        int d = 0;
        while(g[b] != b){
            d ++;
            if(ev[a].ss > ev[b].ss){break;}
            if(ev[a].ss >= ev[b].ff){
                ok = 1; break;
            }
            b = g[b];
        }
        if(ev[a].ss >= ev[b].ff && ev[a].ss <= ev[b].ss && ok == 0){
            d ++; ok = 1; 
        }
        if(ok) cout << d << '\n'; else cout << "impossible\n";
    }
}
 
int main(){
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    int testcases = 1;
    //cin >> testcases;
    while(testcases --){
        solve();
        if(testcases) cout << '\n';
        #ifdef LOCAL
        else cout << '\n';
        cout << "__________________" << endl;
        #endif
    }
    return 0;
}

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