Submission #853885

#	Time	Username	Problem	Language	Result	Execution time	Memory
853885		mychecksedad	Event Hopping (BOI22_events)	C++17	100 / 100	131 ms	26248 KiB

events

/* Author : Mychecksdead */
#include<bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
typedef long double ld;
#define MOD1 (1000000000+7)
#define MOD (998244353)
#define PI 3.1415926535
#define pb push_back
#define setp() cout << setprecision(15)
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " is " << x << '\n';
const int N = 1e6+100, M = 1e5+10, F = 2147483646, K = 20;
 
 
int n, q, t[N], up[N][K];
array<int, 3> a[N], b[N]; // original, sorted by r;
vector<int> all;
 
void build(int l, int r, int k){
    if(l==r){
        t[k] = MOD;
        return;
    }
    int m = (l+r)>>1;
    build(l, m, k<<1);
    build(m+1, r, k<<1|1);
    t[k] = MOD;
}
int get(int l, int r, int ql, int qr, int k){
    if(ql > r || l > qr) return MOD;
    if(ql <= l && r <= qr) return t[k];
    int m = (l+r)>>1;
    return min(get(l, m, ql, qr, k<<1), get(m + 1, r, ql, qr, k<<1|1));
}
 
void update(int l, int r, int p, int k, int val){
    if(p > r || l > p) return;
    if(l == r){
        t[k] = min(t[k], val);
        return;
    }
    int m = (l+r)>>1;
    update(l, m, p, k<<1, val);
    update(m+1, r, p, k<<1|1, val);
    t[k] = min(t[k<<1], t[k<<1|1]);
}
 
bool comp(const array<int, 3> &a, const array<int, 3> &b){
    if(a[1] != b[1])
        return a[1] < b[1];
    return a[0] < b[0];
}
 
void solve(){
    cin >> n >> q;
    for(int i = 1; i <= n; ++i){
        cin >> a[i][0] >> a[i][1];
        all.pb(a[i][0]);
        all.pb(a[i][1]);
        a[i][2] = i;
    }
    
    sort(all(all));
    unique(all(all));
    build(1, 2*n, 1);
 
    for(int i = 1; i <= n; ++i){
        a[i][0] = lower_bound(all(all), a[i][0]) - all.begin() + 1;
        a[i][1] = lower_bound(all(all), a[i][1]) - all.begin() + 1;
        b[i] = a[i];
    }
 
    sort(b + 1, b + 1 + n);
 
    for(int i = 1; i <= n; ++i){
        update(1, 2*n, b[i][1], 1, i);
        a[b[i][2]][2] = i;
    }
    
    for(int i = 1; i <= n; ++i){
        int p = get(1, 2*n, b[i][0], b[i][1], 1);
        up[i][0] = p;
    }

    for(int j = 1; j < K; ++j) for(int i = 1; i <= n; ++i) up[i][j] = up[up[i][j - 1]][j - 1];
    for(;q--;){
        int start, end; cin >> start >> end;
        if(start == end) cout << "0\n";
        else if(a[start][1] > a[end][1]) cout << "impossible\n";
        else if(a[start][1] >= a[end][0]) cout << "1\n";
        else{
            int v = a[end][2], ans = 0;
            for(int j = K - 1; j >= 0; --j){
                if(up[v][j] == v) break;
                if(b[up[v][j]][0] > a[start][1]) v = up[v][j], ans += (1<<j);
            }
            if(b[up[v][0]][0] > a[start][1]){
              cout << "impossible\n";
            }else 
            cout << ans + 2 << '\n';
        }
    }
}
 
 
 
 
int main(){
    cin.tie(0); ios::sync_with_stdio(0);
    int T = 1, aa;
    // cin >> T;aa=T;
    while(T--){
        // cout << "Case #" << aa-T << ": ";
        solve();
    }
    return 0;
 
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:113:16: warning: unused variable 'aa' [-Wunused-variable]
  113 |     int T = 1, aa;
      |                ^~

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