Submission #1027508

#	Time	Username	Problem	Language	Result	Execution time	Memory
1027508		mansur	Fire (BOI24_fire)	C++17	40 / 100	72 ms	28132 KiB

Main

#include<bits/stdc++.h>

using namespace std;

#define rall(s) s.rbegin(), s.rend()
#define all(s) s.begin(), s.end()
#define sz(s) (int)s.size()
#define s second
#define f first

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

const int N = 1e6;
const int inf = 1e9;

int lg[N], up[N][20];

void solve() {
	int n, m;
	cin >> n >> m;
	int l[n + 1], r[n + 1];
	vector<array<int, 3>> s;
	for (int i = 1; i <= n; i++) {
		cin >> l[i] >> r[i];
		if (r[i] < l[i]) r[i] += m;
		s.push_back({l[i], 0, i});
		s.push_back({r[i], 1, i});
	}
	sort(all(s));
	int mx = -1, vt;
	for (auto [p, is, id]: s) {
		if (!is) {
			if (r[id] > mx) {
			 	mx = r[id];
			 	vt = id;
			}
		}else up[id][0] = vt;
	}
	for (int k = 1; k <= lg[n]; k++) {
		for (int i = 1; i <= n; i++) {
			up[i][k] = up[up[i][k - 1]][k - 1];			
		}
	}
	int mn = inf;
	for (int i = 1; i <= n; i++) {
		if (r[i] - l[i] + 1 >= m) {
			mn = 1;
			break;
		}
		int tl = l[i], v = i, ans = 2;
		for (int k = lg[n]; k >= 0; k--) {
            int tr = r[up[v][k]];
            if (tr - tl + 1 >= m) continue;
            v = up[v][k];
            ans += (1 << k);
        }
        v = up[v][0];              
        if (r[v] - tl + 1 < m) continue;
        mn = min(mn, ans);
	}
	if (mn > n) cout << -1;
	else cout << mn;
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	for (int i = 1; i < N; i++) lg[i] = lg[i / 2] + 1;
	solve();
}

Compilation message (stderr)

Main.cpp: In function 'void solve()':
Main.cpp:39:19: warning: 'vt' may be used uninitialized in this function [-Wmaybe-uninitialized]
   39 |   }else up[id][0] = vt;
      |         ~~~~~~~~~~^~~~

• Subtask 1: 14 / 14
• Subtask 2: 17 / 17
• Subtask 3: 9 / 9
• Subtask 4: 0 / 13
• Subtask 5: 0 / 21
• Subtask 6: 0 / 26