Submission #1000157

#	Time	Username	Problem	Language	Result	Execution time	Memory
1000157		OAleksa	Trains (BOI24_trains)	C++14	100 / 100	97 ms	8424 KiB

Main

#include <bits/stdc++.h>
#define f first
#define s second
#define int long long
using namespace std;
const int N = 1e5 + 69;
const int B = 320;
const int mod = 1e9 + 7;
int n, d[N], x[N], dp[N];
vector<int> cnt[B];
vector<tuple<int, int, int>> who[N];
int add(int x, int y) {
	x += y;
	if (x >= mod)
		x -= mod;
	return x;
}
int sub(int x, int y) {
	x -= y;
	x = (x + 1000ll * mod) % mod;
	return x;
}
signed main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int tt = 1;
	//cin >> tt;
	while (tt--) {
		cin >> n;
		for (int i = 1;i <= n;i++) {
			cin >> d[i] >> x[i];
			x[i] = min(x[i], n);
		}
		for (int i = 1;i < B;i++)
			cnt[i].resize(i);
		dp[1] = 1;
		for (int i = 1;i <= n;i++) {
			for (int j = 1;j < B;j++) {
				int x = i % j;
				dp[i] = add(dp[i], cnt[j][x]);
			}
			if (d[i] >= B) {
				for (int j = i + d[i], j1 = 1;j <= n && j1 <= x[i];j += d[i], j1++) {
					dp[j] = add(dp[j], dp[i]);
				}
			}
			else {
				if (d[i] != 0) {
					int when = i + x[i] * d[i];
					if (when <= n) 
						who[when].push_back({d[i], i % d[i], dp[i]});
					cnt[d[i]][i % d[i]] = add(cnt[d[i]][i % d[i]], dp[i]);
				}
			}
			for (auto j : who[i]) {
				int a, b, c;
				tie(a, b, c) = j;
				cnt[a][b] = sub(cnt[a][b], c);
			}
		}
		int ans = 0;
		for (int i = 1;i <= n;i++)
			ans = add(ans, dp[i]);
		cout << ans;
	}
	return 0;
}

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