oj.uz

Submission #860834

# Submission time Handle Problem Language Result Execution time Memory
860834 2023-10-14T15:19:25 Z TahirAliyev Event Hopping (BOI22_events) C++17
0 / 100
 301 ms 19972 KB 
#include <bits/stdc++.h>

#define ll long long
#define pii pair<int, int>
#define oo 1e9

using namespace std;

struct DATA{
    int mn = oo, id;
};

const int MAX = 1e5 + 5, LOGMAX = 21;
int n, q;

pii arr[MAX];
DATA tree[8 * MAX];

DATA comb(DATA a, DATA b){
    if(a.mn < b.mn){
        return a;
    }
    else{
        return b;
    }
}

void update(int node, int l, int r, int pos, int val, int id){
    if(l == r){
        tree[node] = comb({val, id}, tree[node]);
        return;
    }
    int mid = (l + r) / 2;
    if(pos <= mid){
        update(2 * node, l, mid, pos, val, id);
    }
    else{
        update(2 * node + 1, mid + 1, r, pos, val, id);
    }
    tree[node] = comb(tree[2 * node], tree[2 * node + 1]);
}

DATA ask(int node, int l, int r, int ql, int qr){
    if(qr < l || r < ql) return DATA();
    if(ql <= l && r <= qr) return tree[node];
    int mid = (l + r) / 2;
    return comb(ask(2 * node, l, mid, ql, qr), ask(2 * node + 1, mid + 1, r, ql, qr));
}

void compress(){
    vector<pii> v;
    for(int i = 1; i <= n; i++){
        v.push_back({arr[i].first, i});
        v.push_back({arr[i].second, -i});
    }
    sort(v.begin(), v.end());
    int t = 0;
    for(int i = 0; i < 2 * n; i++){
        if(i == 0 || v[i].first != v[i - 1].first){
            t++;
        }
        if(v[i].second > 0){
            arr[v[i].second].first = t;
        }
        else{
            arr[-v[i].second].second = t;
        }
    }
}

int par[LOGMAX][MAX];

bool isReachable(int i, int j){
    return arr[j].first <= arr[i].second && arr[i].second <= arr[j].second;
}

int lift(int s, int d){
    int res = 2;
    if(isReachable(s, d)){
        return 1;
    }
    for(int i = LOGMAX - 1; i >= 0; i--){
        if(!isReachable(s, par[i][d]) && arr[par[i][d]].second >= arr[s].second){
            d = par[i][d];
            res += (1 << i);
        }
    }
    if(!isReachable(s, par[0][d])){
        return -1;
    }
    return res;
}

int main(){
    cin >> n >> q;
    for(int i = 1; i <= n; i++){
        cin >> arr[i].first >> arr[i].second;
    }
    compress();
    for(int i = 1; i <= n; i++){
        update(1, 1, 2 * n, arr[i].second, arr[i].first, i);
    }
    for(int i = 1; i <= n; i++){
        par[0][i] = ask(1, 1, 2 * n, arr[i].first, arr[i].second).id;
    }
    for(int j = 1; j < LOGMAX; j++){
        for(int i = 1; i <= n; i++){
            par[j][i] = par[j - 1][par[j - 1][i]];
        }
    }

    while(q--){
        int s, d; cin >> s >> d;
        int ans = lift(s, d);
        if(ans == -1){
            cout << "impossible\n";
        }
        else{
            cout << ans << '\n';
        }
    }
}

Subtask #1
0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 14684 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #2
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 14684 KB Output is correct
2 Incorrect 2 ms 14852 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #3
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 14684 KB Output is correct
2 Incorrect 2 ms 14852 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #4
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 14684 KB Output is correct
2 Incorrect 2 ms 14852 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #5
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 267 ms 19348 KB Output is correct
2 Correct 274 ms 19352 KB Output is correct
3 Correct 301 ms 19324 KB Output is correct
4 Correct 288 ms 19972 KB Output is correct
5 Incorrect 287 ms 19848 KB Output isn't correct
6 Halted 0 ms 0 KB -

Subtask #6
0 / 30.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 14684 KB Output isn't correct
2 Halted 0 ms 0 KB -