Submission #777282

#	Time	Username	Problem	Language	Result	Execution time	Memory
777282		Cookie	Event Hopping (BOI22_events)	C++14	25 / 100	47 ms	32824 KiB

events

#include<bits/stdc++.h>
#include<fstream>
using namespace std;
ifstream fin("WINTER.inp");
ofstream fout("WINTER.out");
#define sz(v) (int)v.size()
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
const ld PI = 3.14159265359;
const int x[4] = {1, -1, 0, 0};
const int y[4] = {0, 0, 1, -1};
const ll mod = 1e9 + 7;
const int mxn = 1e5 + 5, mxm = 1e5, sq = 400;
const int base = (1 << 18);
const ll inf = 1e9;
const ld pre = 1e-6;
struct th{
    int s, e, id;
    bool operator <(const th &b){
        return(s < b.s);
    }
};
int n, q;
vt<int>comp;
int find(int x){
    return(lower_bound(comp.begin(), comp.end(), x) - comp.begin());
}
pii up[mxn + 1][17];
int pref[mxn + 1][17], s[mxn + 1], e[mxn + 1];
pii get(int l, int r){
    int lg = __lg(r - l + 1);
    return(min(up[l][lg], up[r - (1 << lg) + 1][lg]));
}
signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    cin >> n >> q;
    for(int i = 1; i <= n; i++){
        cin >> s[i] >> e[i];
        comp.pb(s[i]); comp.pb(e[i]); 
    }
    sort(comp.begin(), comp.end());
    for(int i = 0; i < sz(comp); i++){
        up[i][0] = make_pair(inf, 0);
    }
    for(int i = 1; i <= n; i++){
        up[find(e[i])][0] = min(up[find(e[i])][0], make_pair(s[i], i));
    }
    for(int i = 1; i < 17; i++){
        for(int j = 0; j + (1 << i) - 1 < sz(comp); j++){
            up[j][i] = min(up[j][i - 1], up[j + (1 << (i - 1))][i - 1]);
        }
    }
    for(int i = 1; i <= n; i++){
        pref[i][0] = get(find(s[i]), find(e[i])).se;
        
    }
    for(int i = 1; i < 17; i++){
        for(int j = 1; j <= n; j++){
            pref[j][i] = pref[pref[j][i - 1]][i - 1];
        }
    }
    for(int i = 0; i < q; i++){
        int l, r; cin >> l >> r;
        if(l == r){
            cout << 0 << "\n";
        }else if(s[r] <= e[l]){
            if(e[r] >= e[l]){
                cout << 1 << "\n";
            }else{
                cout << "impossible" << "\n";
            }
        }else{
            int ans = 0;
            for(int i = 16; i >= 0; i--){
                int id = pref[r][i];
                
                if(s[id] > e[l]){
                    ans += (1 << i); r = pref[r][i];
                }
            }
            
            r = pref[r][0];
            
            if(s[r] <= e[l] && e[r] >= e[l]){
                cout << ans + 2 << "\n";
            }else{
                cout << "impossible" << "\n";
            }
        }
        
    }
    return(0);
}

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