Submission #1033709

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033709		anHiep	Trains (BOI24_trains)	C++14	100 / 100	159 ms	9492 KiB

Main

//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

#include<bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pb push_back
#define ll long long
#define ii pair<int, int>
#define vi vector<int>
#define vll vector<ll>
#define vii vector<ii>
#define cd complex<double>
#define ld long double
#define all(x) (x).begin(), (x).end()
#define iii tuple<int, int, int>
const ll mod = 1e9 + 7;
const ll INF = 1e18L + 5;
const double PI = acos(-1);
const int block = 320;
const int N = 1e5;
int tc, tt = 1;

int n;
ll d[N + 5], x[N + 5];

namespace sub1 {
    bool ck() {
        return n <= 15;
    }
    ll dp[N + 5];
    void sol() {
        dp[1] = 1;
        for(int i=1; i<=n; i++) if(d[i] != 0) {
            for(int j=i + d[i]; j<=min(1LL*n, i + x[i] * d[i]); j+=d[i]) 
                dp[j] = (dp[j] + dp[i]) % mod;
        }
        ll ans = 0;
        for(int i=1; i<=n; i++) ans = (ans + dp[i]) % mod;
        cout<<ans;
    }
}

namespace sub2 {
    bool ck() {
        return true;
    }
    struct node {
        ll i, j, d;
    };
    ll dp[N + 5], sum[block + 100][block + 100];
    vector<node> end[N + 5];
    void sol() {
        memset(sum, 0, sizeof(sum));
        dp[1] = 1;
        for(int i=1; i<=n; i++) {
            for(int j=1; j<=block; j++)
                    dp[i] = (dp[i] + sum[j][i % j]) % mod;
            for(auto x: end[i])
                sum[x.i][x.j] = (sum[x.i][x.j] + mod - x.d) % mod;
            if(d[i] == 0) continue;
            if(d[i] > block) {
                for(int j=i + d[i]; j<=min(1LL * n, i + x[i] * d[i]); j+=d[i]) 
                    dp[j] = (dp[j] + dp[i]) % mod;
            }
            else {
                if(x[i] == 0) continue;
                if(i + x[i] * d[i] <= n)
                    end[i + x[i] * d[i]].pb({d[i], i % d[i], dp[i]});
                sum[d[i]][i % d[i]] = (sum[d[i]][i % d[i]] + dp[i]) % mod;
            }
        }
        ll ans = 0;
        for(int i=1; i<=n; i++) ans = (ans + dp[i]) % mod;
        cout<<ans;
    }
}

void solve() {
    cin>>n;
    for(int i=1; i<=n; i++) cin>>d[i]>>x[i];
    if(sub1::ck()) {sub1::sol(); return;}
    if(sub2::ck()) {sub2::sol(); return;}
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    for(tc=1; tc<=tt; tc++) solve();
    cerr<<"\nTime elapsed: "<<1000.0*clock()/CLOCKS_PER_SEC<<" ms.\n";
    return 0;
}

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