Submission #1033609

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033609		KhoaDuy	Trains (BOI24_trains)	C++14	100 / 100	249 ms	251704 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
const int mod=1e9+7;
const int MAXN=1e5;
const int block=317;
int sum[MAXN+1][block+1];
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    memset(sum,0,sizeof(sum));
    int n;
    cin >> n;
    int DP[n+1];
    int x[n+1];
    int d[n+1];
    for(int i=1;i<=n;i++){
        cin >> d[i] >> x[i];
    }
    for(int i=n;i>=1;i--){
        DP[i]=1;
        if(d[i]){
            if(d[i]>block){
                for(int j=i+d[i];j<=min(n,i+x[i]*d[i]);j+=d[i]){
                    DP[i]+=DP[j];
                    DP[i]%=mod;
                }
            }
            else{
                if(i+d[i]<=n){
                    int curr=sum[i+d[i]][d[i]];
                    int minu=0;
                    if((i+(x[i]+1)*d[i])<=n){
                        minu=sum[i+(x[i]+1)*d[i]][d[i]];
                    }
                    curr=(curr-minu+mod)%mod;
                    DP[i]+=curr;
                    DP[i]%=mod;
                }
            }
        }
        for(int j=1;j<=block;j++){
            sum[i][j]=DP[i];
            if(i+j<=n){
                sum[i][j]+=sum[i+j][j];
                sum[i][j]%=mod;
            }
        }
    }
    cout << DP[1];
}

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