Submission #1241648

#	Time	Username	Problem	Language	Result	Execution time	Memory
1241648		tminh	Trains (BOI24_trains)	C++20	100 / 100	194 ms	6420 KiB

Main

#include "bits/stdc++.h"
using namespace std;

#define task ""
#define ll long long
#define endl '\n'
#define fi first
#define se second
#define vall(a) (a).begin(), (a).end()
#define sze(a) (int)a.size()
#define pii pair<int, int>
#define pll pair<ll, ll>


#define ep emplace_back
#define pb push_back
#define pf push_front


const ll mod = 1e9 + 7;
const int N = 1e5 + 5;
const ll oo = 1e18;
const int base = 300;

bool START;


int n, d[N], x[N];
ll dp[N], f[base + 5][base + 5];
vector<int> del[N];

ll Mod(ll x) {
	if (x >= mod) return x - mod;
	if (x < 0) return x + mod;
	return x;
}

inline void solve() {
	dp[0] = 1;
	ll ans = 0;
	for (int i = 0; i < n; ++i) {
		
		for (int j : del[i]) f[d[j]][j % d[j]] = Mod(f[d[j]][j % d[j]] - dp[j]);
		for (int j = 1; j <= base; ++j) dp[i] = Mod(dp[i] + f[j][i % j]);
		
		if (!d[i] || d[i] > n) {
			ans = Mod(ans + dp[i]);
			continue;
		}
		if (d[i] > base) {
			for (int j = 1; i + j * d[i] < n && j <= x[i]; ++j) dp[i + j * d[i]] = Mod(dp[i + j * d[i]] + dp[i]);
		} else {
			f[d[i]][i % d[i]] = Mod(f[d[i]][i % d[i]] + dp[i]);
			ll lim = i + 1ll * d[i] * (x[i] + 1);
			if (lim <= n) del[lim].pb(i);
		}
		ans = Mod(ans + dp[i]);
	}
	cout << ans;
}


inline void input() {
    cin >> n;
    for (int i = 0; i < n; ++i) cin >> d[i] >> x[i];
    return solve();
}
bool END;

int main() {
    if(fopen(task ".inp", "r")) {
        freopen(task ".inp", "r", stdin);
        freopen(task ".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);

    input();
    
    
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << 's' << endl;
    cerr << "Memory: " << fabs ((&END - &START)) / 1048576.0 << "MB\n";
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen(task ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:73:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen(task ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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