Submission #729451

#	Time	Username	Problem	Language	Result	Execution time	Memory
729451		Sam_a17	Event Hopping (BOI22_events)	C++17	10 / 100	1570 ms	42840 KiB

events

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;

#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif

#define sz(x) (int)x.size()
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount

#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long

void print(long long t) { cerr << t; }
void print(int t) { cerr << t; }
void print(string t) { cerr << t; }
void print(char t) { cerr << t; }
void print(double t) { cerr << t; }
void print(long double t) { cerr << t; }
void print(unsigned long long t) { cerr << t; }

template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[], V n) { cerr << "["; for (int i = 0; i < n; i++) { print(v[i]); cerr << " "; } cerr << "]"; }
template <class T, class V> void print(pair <T, V> p) { cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}"; }
template <class T> void print(vector <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(set <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(multiset <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T, class V> void print(map <T, V> v) { cerr << "[ "; for (auto i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T, class V> void print(unordered_map <T, V> v) { cerr << "[ "; for (auto i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(deque <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'

// for random generations
mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
// mt19937 myrand(131);

// for grid problems
int dx[8] = { -1,0,1,0,1,-1,1,-1 };
int dy[8] = { 0,1,0,-1,1,1,-1,-1 };

// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
	fastIO();

	if (str == "input") {
		freopen("input.txt", "r", stdin);
		freopen("output.txt", "w", stdout);
	}
	else {
		// freopen("skis.in", "r", stdin);
		// freopen("skis.out", "w", stdout);
	}
}
// Indexed Set  
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 2e5 + 10, M = 5e3 + 10, inf = 1e8;
vector<int> adj[N];
int n, q, l[N], r[N];
int dist[M][M];

void bfs(int node) {
	queue<int> q;
	q.push(node);
	vector<bool> vis(n + 1);
	vis[node] = true;
	for(int i = 1; i <= n; i++) {
		dist[node][i] = inf;
	}
	dist[node][node] = 0;

	while(!q.empty()) {
		auto u = q.front();
		q.pop();

		for(auto i: adj[u]) {
			if(vis[i]) continue;
			dist[node][i] = dist[node][u] + 1;
			vis[i] = true;
			q.push(i);
		}
	}
}

void solve_() {
	cin >> n >> q;

	for(int i = 1; i <= n; i++) {
		cin >> l[i] >> r[i];
	}

	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= n; j++) {
			if(i == j) continue;
			if(r[i] >= l[j] && r[i] <= r[j]) {
				adj[i].push_back(j);
			}
		}
	}

	for(int i = 1; i <= n; i++) {
		bfs(i);
	}

	while(q--) {
		int x, y; cin >> x >> y;
		if(dist[x][y] == inf) {
			cout << "impossible" << '\n';
		} else {
			cout << dist[x][y] << '\n';
		}
	}

}

int main() {
	setIO();

	auto solve = [&](int test_case)-> void {
		for (int i = 1; i <= test_case; i++) {
			solve_();
		}
	};

	int test_cases = 1;
	// cin >> test_cases;
	solve(test_cases);

	return 0;
}

Compilation message (stderr)

events.cpp: In function 'void setIO(std::string)':
events.cpp:69:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |   freopen("input.txt", "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
events.cpp:70:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |   freopen("output.txt", "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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