Submission #1033681

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033681		kustizus	Trains (BOI24_trains)	C++17	100 / 100	122 ms	19060 KiB

Main

// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,fma,bmi2,popcnt,lzcnt")
#include <bits/stdc++.h>
#define int long long
using namespace std;
mt19937_64 rnd(chrono::high_resolution_clock::now().time_since_epoch().count());
const int N=1e5,MOD=1e9+7;
int n,x[N+5],d[N+5],m[320][320],dp[N+5];
map <pair<int,int>,int> mp[N+5];
vector <pair<int,int>> v[N+5];
void Solve(){
    cin>>n;
    int block=sqrt(n);
    for (int i=1;i<=n;++i){
        cin>>d[i]>>x[i];
        int o=i+d[i]*x[i];
        if (o+d[i]<=n) v[o].push_back({d[i],x[i]});
    }
    for (int i=n;i>=1;--i){
        dp[i]=1;
        if (!d[i] || !x[i]) dp[i]=1;
        else if (d[i]>block){
            int j=i+d[i];
            while (j<=n){
                dp[i]+=dp[j];
                j+=d[i];
            }
            dp[i]%=MOD;
        }
        else dp[i]=m[d[i]][i%d[i]]+1;
        for (pair <int,int> p : v[i]){
            int d=p.first,x=p.second;
            if (!d || !x) mp[i][p]=0;
            else if (d>block){
                int j=i+d,val=0;
                while (j<=n){
                    val+=dp[j];
                    j+=d;
                }
                val%=MOD;
                mp[i][p]=val;
            }
            else mp[i][p]=m[d][i%d];
        }
        if (d[i] && x[i]){
            int o=i+d[i]*x[i];
            if (o+d[i]<=n) dp[i]-=mp[o][{d[i],x[i]}];
            dp[i]=(dp[i]%MOD+MOD)%MOD;
        }
        for (int j=1;j<=block;++j) m[j][i%j]=(m[j][i%j]+dp[i])%MOD;
    }
    cout<<dp[1];
}
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    // freopen ("FILE.INP","r",stdin);
    // freopen ("FILE.OUT","w",stdout);
    int t=1;
    while (t--) Solve();
    cerr<<"\nTIME: "<<1000*clock()/CLOCKS_PER_SEC<<"ms\n";
}

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