Submission #1123487

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123487		Pwo	Trains (BOI24_trains)	C++17	71 / 100	486 ms	10176 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int m = 1e9 + 7;

int n, dp[100005];
pair<int, int> a[100005];
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
unordered_map<int, int> rem[100005];

int32_t main() {
	ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
	cin >> n;
	for (int i = 1; i <= n; i++) cin >> a[i].first >> a[i].second;
	dp[1] = 1;
	
	bool b = 1;
	for (int i = 1; i <= n; i++) if (a[i].first != 1) b = 0;
	
	if (n <= 10000) {
		for (int i = 2; i <= n; i++) {
			for (int j = 1; j < i; j++) {
				if (a[j].first == 0) continue;
				int d = i - j;
				if (d % a[j].first == 0
					&& (d / a[j].first) <= a[j].second)
					dp[i] = (dp[i] + dp[j]) % m;
			}
		}
	} else if (b) {
		int sum = 1;
		pq.emplace(a[1].second + 1, 1);
		for (int i = 2; i <= n; i++) {
			while (!pq.empty() && pq.top().first < i) {
				sum = (sum + m - pq.top().second) % m;
				pq.pop();
			}
			dp[i] = sum;
			sum = (sum + dp[i]) % m;
			pq.emplace(i + a[i].second, dp[i]);
		}
	} else {
		vector<int> v;
		unordered_map<int, int> tmp;
		for (int i = 1; i <= n; i++) {
			if (tmp.find(a[i].first) == tmp.end()) {
				tmp[a[i].first] = v.size();
				v.push_back(a[i].first);
			}
		}

		rem[0][1 % a[1].first] = 1;
		for (int i = 2; i <= n; i++) {
			for (int idx = 0; idx < v.size(); idx++) {
				int md = v[idx];
				int r = i % md;
				dp[i] = (dp[i] + rem[idx][r]) % m;
			}

			int idx = tmp[a[i].first];
			int r = i % a[i].first;
			rem[idx][r] = (rem[idx][r] + dp[i]) % m;
		}
	}

	int ans = 0;
	for (int i = 1; i <= n; i++) ans = (ans + dp[i]) % m;
	cout << ans;
}

• Subtask 1: 8 / 8
• Subtask 2: 13 / 13
• Subtask 3: 16 / 16
• Subtask 4: 34 / 34
• Subtask 5: 0 / 29