Submission #1273965

#	Time	Username	Problem	Language	Result	Execution time	Memory
1273965		torment	Trains (BOI24_trains)	C++20	100 / 100	143 ms	118628 KiB

Main

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
const int B = 300;
const int MOD = 1e9 + 7;
int dp[N], S[B][N];
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin >> n;
    vector<array<int, 2>>v(n);
    for(int i = 0;i < n;++i){
        cin >> v[i][0] >> v[i][1];
    }
    for(int i = n - 1;i >= 0;--i){
        int d = v[i][0], x = v[i][1];
        dp[i] = 1;
        for(int j = 1;j < B;++j){
            if(i + j < n)S[j][i] = (S[j][i + j] + dp[i + j]) % MOD;
        }
        if(d >= B){
            for(int j = 1;j <= x && i + j * 1ll * d < n;++j){
                dp[i] += dp[i + j * d];
                dp[i] %= MOD;
            }
        }
        else{
            int num = min(1ll * n, i + d * 1ll * x);
            dp[i] += (S[d][i] - S[d][num] + MOD) % MOD;
        }
    }
    cout << dp[0] << '\n';
}

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