Submission #1065166

#	Time	Username	Problem	Language	Result	Execution time	Memory
1065166		ttttttttttttth	Trains (BOI24_trains)	C++17	100 / 100	182 ms	29580 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define int long long

const long long N = 1e5 + 5;
const long long inf = 1e9;
const long long mod = 1e9 + 7;
const int Block = 27;

int n, d[N], x[N];
int dp[N], f[N][Block + 5];

signed main() {
    ios_base :: sync_with_stdio (0);
    cin.tie (0);
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> d[i] >> x[i];
    }
    for (int i = n; i >= 1; i--) {
        dp[i] = 0;
        if (d[i] == 0) {
            dp[i] = 1;
        } 
        else if (d[i] > Block) {
            for (int j = i + d[i]; j <= min(n, i + d[i] * x[i]); j += d[i]) {
                dp[i] = (dp[i] + dp[j]) % mod;
            }
            dp[i] = (dp[i] + 1) % mod;
        } 
        else {
            dp[i] = 1;
            dp[i] = (dp[i] + ((i + d[i] <= n) ? (f[i + d[i]][d[i]]) : 0)) % mod;
            dp[i] = (dp[i] - ((i + d[i] * (x[i] + 1) <= n) ? (f[(i + d[i] * (x[i] + 1))][d[i]]) : 0) + mod * mod) % mod;
        }
        for (int j = 0; j <= Block; j++) {
            f[i][j] = ((i + j <= n ? f[i + j][j] : 0) + dp[i]) % mod;
        }
    }
    cout << dp[1];
}

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