Submission #580864

#	Time	Username	Problem	Language	Result	Execution time	Memory
580864		talant117408	Event Hopping (BOI22_events)	C++17	10 / 100	1599 ms	42624 KiB

events

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;

#define long                unsigned long 
#define pb                  push_back
#define mp                  make_pair
#define all(v)              (v).begin(),(v).end()
#define rall(v)             (v).rbegin(),(v).rend()
#define lb                  lower_bound
#define ub                  upper_bound
#define sz(v)               int((v).size())
#define do_not_disturb      ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl                '\n'

const int N = 1e5+7;
vector <int> graph[N];
int shortest[5003][5003];
int s[N], e[N], n;

void bfs(int p) {
    for (int i = 1; i <= n; i++) {
        shortest[p][i] = 2e9;
    }
    shortest[p][p] = 0;
    queue <int> K;
    K.push(p);
    
    while (!K.empty()) {
        auto v = K.front(); K.pop();
        for (auto to : graph[v]) {
            if (shortest[p][to] > shortest[p][v] + 1) {
                shortest[p][to] = shortest[p][v] + 1;
                K.push(to);
            }
        }
    }
}

void solve() {
    int q;
    cin >> n >> q;
    for (int i = 1; i <= n; i++) {
        cin >> s[i] >> e[i];
    }
    vector <pii> queries(q);
    for (auto &to : queries) cin >> to.first >> to.second;
    
    if (n <= 5000) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                if (i == j) continue;
                if (s[j] <= e[i] && e[i] <= e[j]) graph[i].pb(j);
            }
        }
        for (int i = 1; i <= n; i++) bfs(i);
        for (auto to : queries) {
            if (shortest[to.first][to.second] > 1e9) cout << "impossible" << endl;
            else cout << shortest[to.first][to.second] << endl;
        }
    }
}

int main() {
    do_not_disturb
    
    int t = 1;
    //~ cin >> t;
    while (t--) {
        solve();
    }
    
    return 0;
}

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