Submission #1026265

#	Time	Username	Problem	Language	Result	Execution time	Memory
1026265		mareksb	Trains (BOI24_trains)	C++17	0 / 100	18 ms	13148 KiB

Main

#include <bits/stdc++.h>

using namespace std;
constexpr int N = 1e5+5;
constexpr int mod = 1e9+7;
int dp[N]{};//number of paths starting from i
constexpr int d=320;
int c[N+5][d]{};//sum dp given (start pos, step size)
int main() {
    int n;
    cin>>n;
    int a[n+1],b[n+1];
    for(int i=1;i<=n;i++){
        cin>>a[i]>>b[i];
    }
    for(int i=n;i>0;i--){
        dp[i]=1;
        if(a[i]){
            if(a[i]>=d){
                for(int j=1;j<=b[i];j++){
                        int pos=i+j*a[i];
                        if(pos>n)break;
                        dp[i]=(dp[i]+dp[pos])%mod;
                }
            }
            else{
                int fin = min(i+a[i]*b[i],n);
                dp[i]=(dp[i]+c[i][a[i]]-c[fin][a[i]])%mod;
            }
        }
        //update c state
        for(int j=1;j<d;j++){
            if(i-j<1)break;
            c[i-j][j]=(c[i][j]+dp[i])%mod;
        }
    }
    cout<<dp[1]<<' ';

}

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