Submission #598885

#	Time	Username	Problem	Language	Result	Execution time	Memory
598885		radal	Event Hopping (BOI22_events)	C++17	100 / 100	143 ms	15056 KiB

events

#include <bits/stdc++.h>
//#pragma GCC target("sse,sse2,avx2")
#pragma GCC optimize("unroll-loops,O3")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pll;
constexpr int N = 1e5+20,mod = 1e9+7,inf = 1e9+10,sq = 500;
inline int mkay(int a,int b){
    if (a+b >= mod) return a+b-mod;
    if (a+b < 0) return a+b+mod;
    return a+b;
}
 
inline int poww(int a,int k){
    if (k < 0) return 0;
    int z = 1;
    while (k){
        if (k&1) z = 1ll*z*a%mod;
        a = 1ll*a*a%mod;
        k >>= 1;
    } 
    return z; 
}
int s[N],e[N],sp[N][20],seg[N*4];
vector<pll> ve;
bool cmp(pll i,pll j){
    if (e[i.Y] == e[j.Y]) return (s[i.Y] < s[j.Y]);
    return (e[i.Y] < e[j.Y]);
}
void build(int l,int r,int v = 1){
    if (r-l == 1){
        seg[v] = ve[l].Y;
        return;
    }
    int u = (v << 1),m = (l+r) >> 1;
    build(l,m,u);
    build(m,r,u|1);
    if (s[seg[u]] < s[seg[u|1]]) seg[v] = seg[u];
    else seg[v] = seg[u|1];
}
int que(int l,int r,int S,int E,int v = 1){
    if (S == l && r == E) return seg[v];
    int m = (l+r) >> 1,u = (v << 1);
    if (E <= m) return que(l,m,S,E,u);
    if (S >= m) return que(m,r,S,E,u|1);
    int x = que(l,m,S,m,u),y = que(m,r,m,E,u|1);
    if (s[x] < s[y]) return x;
    return y;
}
int main(){
    ios :: sync_with_stdio(0); cin.tie(0);
    int n,q;
    cin >> n >> q;
    rep(i,1,n+1){
        cin >> s[i] >> e[i];
        ve.pb({e[i],i});
    }
    sort(all(ve),cmp);
    build(0,n,1);
    rep(i,0,n){
        int j = ve[i].Y;
        int ind = lower_bound(all(ve),make_pair(s[j],0))-ve.begin();
        sp[j][0] = que(0,n,ind,i+1,1);
    }
    rep(j,1,20){
        rep(i,1,n+1){
            sp[i][j] = sp[sp[i][j-1]][j-1];
        }
    }
    while (q--){
        int a,b;
        cin >> a >> b;
        if (a == b){
            cout << 0 << endl;
            continue;
        }
        if (e[a] > e[b] || s[sp[b][19]] > s[a]){
            cout << "impossible" << endl;
            continue;
        }
        if (e[a] == e[b]){
            cout << 1 << endl;
            continue;
        }
        int x = 0;
        repr(i,19,0){
            if (s[sp[b][i]] > e[a]){
                x += (1 << i);
                b = sp[b][i];
            }
        }
        x++;
        if (e[a] < s[b]) x++;
        cout << x << endl;
    }
    return 0;
}

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