oj.uz

Submission #660540

# Submission time Handle Problem Language Result Execution time Memory
660540 2022-11-22T08:11:43 Z mychecksedad Event Hopping (BOI22_events) C++17
0 / 100
 182 ms 18516 KB 
/* 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;


struct Dsu{
    vector<int> p, s;
    Dsu(int n){
        p.resize(n+1);
        s.resize(n+1, 1);
        for(int i = 1; i <= n; ++i) p[i] = i;
    }
    int find(int v){
        if(p[v] == v) return v;
        return (p[v] = find(p[v]));
    }
    void merge(int a, int b){
        a = find(a);
        b = find(b);
        if(a != b){
            if(s[a] > s[b]) swap(a, b);
            p[a] = b;
            s[b] += s[a];
        }
    }
};


int n, q, t[N], up[N][K], tmin[N];
array<int, 3> a[N], b[N];
vector<int> all;
void build(int l, int r, int k){
    if(l==r){
        t[k] = 0;
        tmin[k] = MOD;
        return;
    }
    int m = (l+r)>>1;
    build(l, m, k<<1);
    build(m+1, r, k<<1|1);
    t[k] = 0;
    tmin[k] = MOD;
}
int get(int l, int r, int p, int k){
    if(p > r || l > p) return 0;
    if(l == r) return t[k];
    int m = (l+r)>>1;
    return max({t[k], get(l, m, p, k<<1), get(m+1, r, p, k<<1|1)});
}
int getmin(int l, int r, int p, int k){
    if(p > r || l > p) return MOD;
    if(l == r) return tmin[k];
    int m = (l+r)>>1;
    return min({tmin[k], getmin(l, m, p, k<<1), getmin(m+1, r, p, k<<1|1)});
}
void update(int l, int r, int ql, int qr, int k, int val){
    if(ql > r || l > qr) return;
    if(ql <= l && r <= qr){
        t[k] = max(val, t[k]);
        return;
    }
    int m = (l+r)>>1;
    update(l, m, ql, qr, k<<1, val);
    update(m+1, r, ql, qr, k<<1|1, val);
}
void updatemin(int l, int r, int ql, int qr, int k, int val){
    if(ql > r || l > qr) return;
    if(ql <= l && r <= qr){
        tmin[k] = min(val, tmin[k]);
        return;
    }
    int m = (l+r)>>1;
    updatemin(l, m, ql, qr, k<<1, val);
    updatemin(m+1, r, ql, qr, k<<1|1, val);
}
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;
    }
    
    Dsu d(n);
    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(a + 1, a + 1 + n, comp);
    
    for(int i = 1; i <= n; ++i){
        update(1, 2*n, a[i][0], a[i][1], 1, i);
        updatemin(1, 2*n, a[i][0], a[i][1], 1, i);
        b[a[i][2]][2] = i;
    }
    for(int i = 1; i <= n; ++i){
        int p = get(1, 2*n, a[i][1], 1);
        d.merge(a[i][2], a[p][2]);
        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 s, e; cin >> s >> e;
        if(s == e) cout << "0\n";
        else if(d.find(s) != d.find(e) || b[s][1] > b[e][1]) cout << "impossible\n";
        else{
            int v = b[s][2], ans = 0;
            for(int j = K - 1; j >= 0; --j){
                if(a[up[v][j]][1] < b[e][0]) v = up[v][j], ans += (1<<j);
            }
            int last = getmin(1, 2*n, b[e][0], 1);
            if(a[last][0] > a[v][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

events.cpp: In function 'int main()':
events.cpp:146:16: warning: unused variable 'aa' [-Wunused-variable]
  146 |     int T = 1, aa;
      |                ^~

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 176 ms 16768 KB Output is correct
3 Correct 172 ms 16760 KB Output is correct
4 Incorrect 178 ms 18516 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #2
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 468 KB Output is correct
4 Incorrect 2 ms 468 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 468 KB Output is correct
4 Incorrect 2 ms 468 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 1 ms 468 KB Output is correct
4 Incorrect 2 ms 468 KB Output isn't correct
5 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 172 ms 16724 KB Output is correct
2 Correct 157 ms 16868 KB Output is correct
3 Incorrect 182 ms 18468 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 340 KB Output is correct
2 Correct 176 ms 16768 KB Output is correct
3 Correct 172 ms 16760 KB Output is correct
4 Incorrect 178 ms 18516 KB Output isn't correct
5 Halted 0 ms 0 KB -