Submission #1069983

#	Time	Username	Problem	Language	Result	Execution time	Memory
1069983		mindiyak	Event Hopping (BOI22_events)	C++14	0 / 100	196 ms	11844 KiB

events

#pragma GCC optimize("O1,O2,O3,Ofast,unroll-loops")
#include <bits/stdc++.h>
#include <string>
#include <iostream>
#include <cmath>
#include <numeric>
#include <stack>
#include <queue>
#include <set>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ld, ld> pd;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<pi>> vvpi;
typedef vector<ld> vd;
typedef vector<long long> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define len(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define F first
#define nl endl
#define S second
#define lb lower_bound
#define ub upper_bound
#define aint(x) x.begin(), x.end()
#define raint(x) x.rbegin(), x.rend()
#define ins insert
const int M = 1e9+7;
void init(string name)
{
    freopen((name + ".in").c_str(), "r", stdin);
    freopen((name + ".out").c_str(), "w", stdout);
}
void fastIO()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
}
 
int n,q;
vector<pair<pi,int>> arr;
vvi paths(1e5+5);
 
void solve()
{   
    cin >> n >> q;
    FOR(i,0,n){
        int a,b;cin >> a >> b;
        arr.pb({{a,b},i+1});
    }
    sort(arr.begin(),arr.end());

    FOR(i,0,n-1){
        FOR(j,i+1,i+2){
            // cerr << i << " " << j << " " << arr[j].F.F << " " << arr[i].F.S << " " << arr[i].F.F << endl;
            if(arr[j].F.F <= arr[i].F.S && arr[j].F.S >= arr[i].F.S){
                paths[arr[i].S].pb(arr[j].S);
            }
        }
    }

    vi head(n+2,-1);
    vi dist(n+2,-1);

    FOR(i,1,n+1){
        if(head[i] != -1)continue;

        head[i] = i;
        dist[i] = 0;
        queue<int> q;
        q.push(i);
        while(!q.empty()){
            int a = q.front();q.pop();
            for(int b:paths[a]){
                head[b] = i;
                dist[b] = dist[a] + 1;
                q.push(b);
            }
        }
    }

    // FOR(i,1,n+1){
    //     cerr << i << " -> ";
    //     for(int a:paths[i])cerr << a << " ";
    //     cerr << endl;
    // }cerr << endl;

    // FOR(i,1,n+1){
    //     cerr << head[i] << " ";
    // }cerr << endl;

    // FOR(i,1,n+1){
    //     cerr << dist[i] << " ";
    // }cerr << endl;

    FOR(i,0,q){
        int a,b;cin >> a >> b;
        if(head[a] != head[b])cout << "impossible" << endl;
        else if((head[a] == head[b]) && (dist[a] > dist[b]))cout << "impossible" << endl;
        else cout << dist[b] - dist[a] << endl;
    }
}   
 
 
int main()
{
    fastIO();
    // init("test");
    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}

Compilation message (stderr)

events.cpp: In function 'void init(std::string)':
events.cpp:45:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |     freopen((name + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:46:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |     freopen((name + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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