Submission #1287598

#	Time	Username	Problem	Language	Result	Execution time	Memory
1287598		vahagng	Trains (BOI24_trains)	C++20	21 / 100	71 ms	10468 KiB

Main

//----------vahagng----------//
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
using namespace std;
// using namespace __gnu_pbds;

// template <class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif

void print(long long t) { cerr << t; }
void print(int t) { cerr << t; }
void print(string t) { cerr << t; }
void print(char t) { cerr << t; }
void print(double t) { cerr << t; }
void print(long double t) { cerr << t; }
void print(unsigned long long t) { cerr << t; }

template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(T v[], V n) { cerr << "["; for (int i = 0; i < n; i++) { cerr << v[i] << " "; } cerr << "]"; }
template <class T, class V> void print(pair <T, V> p) { cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}"; }
template <class T> void print(vector <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(set <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T> void print(multiset <T> v) { cerr << "[ "; for (T i : v) { print(i); cerr << " "; } cerr << "]"; }
template <class T, class V> void print(map <T, V> v) { cerr << "[ "; for (auto i : v) { print(i); cerr << " "; } cerr << "]"; }

#define ll long long
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define ld long double
#define sz(v) v.size()
#define endl '\n'

const ll inf = 2e18, mod = 1e9 + 7, mod2 = 998244353;

void SetIO(string str = "") {
    if (str != "") {
        freopen((str + ".in").c_str(), "r", stdin);
        freopen((str + ".out").c_str(), "w", stdout);
    }
    else {
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    }
}

void FastIO() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
}

const int N = 2e5 + 10, M = 1e7 + 10;

mt19937 rnd(chrono::system_clock::now().time_since_epoch().count());

ll binpow(ll a, ll b) {
    ll res = 1;
    while (b) {
        if (b & 1) {
            res = (res * a) % mod;
        }
        b >>= 1;
        a = (a * a) % mod;
    }
    return res;
}

ll n, a[N], b[N], dp[N];

struct segtree{
    struct Node{
        ll mx, lazy;
    };
    int size = 1;
    vector<Node>stree;

    void init(){
        while(size < n) size <<= 1;
        stree.assign(4*size, {0,0});
    }

    void push(int x, int lx, int rx){
        if(rx - lx == 1) return;
        stree[2*x+1].lazy += stree[x].lazy;
        stree[2*x+1].lazy %= mod;
        stree[2*x+2].lazy += stree[x].lazy;
        stree[2*x+2].lazy %= mod;
        stree[2*x+1].mx += stree[x].lazy;
        stree[2*x+1].mx %= mod;
        stree[2*x+2].mx += stree[x].lazy;
        stree[2*x+2].mx %= mod;
        stree[x].lazy = 0;
    }

    void upd(int l, int r, ll v, int x, int lx, int rx){
        push(x, lx, rx);
        if(lx >= l && rx <= r){
            stree[x].lazy += v;
            stree[x].mx += v;
            return;
        }
        if(lx >= r || rx <= l) return;
        int m = (lx + rx)/2;
        upd(l, r, v, 2*x+1, lx, m);
        upd(l, r, v, 2*x+2, m, rx);
        stree[x].mx = max(stree[2*x+1].mx, stree[2*x+2].mx);
    }

    ll qry(int l, int r, int x, int lx, int rx){
        push(x, lx, rx);
        if(lx >= l && rx <= r) return stree[x].mx;
        if(lx >= r || rx <= l) return 0;
        int m = (lx + rx)/2;
        return max(qry(l, r, 2*x+1, lx, m), qry(l, r, 2*x+2, m, rx));
    }

    void upd(int l, int r, ll v){
        upd(l, r, v, 0, 0, size);
    }

    ll qry(int i){
        return qry(i, i + 1, 0, 0, size);
    }
}st;

void solve(int tc) {
    cin >> n;
    for(int i = 1; i <= n; i++){
        cin >> b[i] >> a[i];
    }
    if(n <= 10000){
        dp[1] = 1;
        for(int i = 1; i < n; i++){
            if(b[i] == 0) continue;
            for(int t = 1; t <= a[i]; t++){
                int j = t * b[i] + i;
                if(j > n) break;
                dp[j] = (dp[i] + dp[j])%mod;
            }
        }
        ll ans = 0;
        for(int i = 1; i <= n; i++){
            ans = (ans + dp[i])%mod;
        }
        cout << ans << endl;
        return;
    }
    st.init();
    st.upd(1, 2, 1);
    for(int i = 1; i <= n; i++){
        dp[i] = st.qry(i);
        if(b[i] == 0) continue;
        int j = min(n, i + b[i]);
        st.upd(i+1, j + 1, dp[i]);
    }
    ll ans = 0;
    for(int i = 1; i <= n; i++){
        ans += dp[i];
        ans %= mod;
    }
    cout << ans << endl;
}


void precalc() {
    
}

int main() {
    // SetIO("teamwork");
    FastIO();
    int test_case = 1;
    // cin >> test_case;
    precalc();
    int cnt = 1;
    while (test_case--) {
        solve(cnt++);
    }
    return 0;
}

Compilation message (stderr)

Main.cpp: In function 'void SetIO(std::string)':
Main.cpp:47:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         freopen((str + ".in").c_str(), "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:48:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         freopen((str + ".out").c_str(), "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:51:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |         freopen("input.txt", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:52:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   52 |         freopen("output.txt", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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