//----------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 lazy, sum;
};
int size = 1;
vector<Node>stree;
void init(){
while(size <= n) size <<= 1;
stree.assign(4*size, {});
}
void push(int x, int lx, int rx){
if(rx - lx == 1){
return;
}
stree[2*x+1].lazy += stree[x].lazy;
stree[2*x+2].lazy += stree[x].lazy;
int m = (lx + rx)/2;
stree[2*x+1].sum += (m - lx)*stree[x].lazy;
stree[2*x+2].sum += (rx - m)*stree[x].lazy;
stree[x].lazy = 0;
}
void upd(int l, int r, ll v, int x, int lx, int rx){
push(x, lx, rx);
if(lx >= r || rx <= l) return ;
if(lx >= l && rx <= r){
stree[x].lazy += v;
stree[x].sum += (rx - lx)*v;
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].sum = stree[2*x+1].sum + stree[2*x+2].sum;
}
ll qry(int l, int r, int x, int lx, int rx){
push(x, lx, rx);
if(lx >= r || rx <= l){
return 0;
}
if(lx >= l && rx <= r){
return stree[x].sum;
}
int m = (lx + rx)/2;
ll ans_l = qry(l, r, 2*x+1, lx, m);
ll ans_r = qry(l, r, 2*x+2, m, rx);
return ans_l + ans_r;
}
void upd(int l, int r, ll val){
upd(l, r, val, 0, 0, size);
}
ll qry(int l, int r){
return qry(l, r, 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, i + 1);
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;
}
컴파일 시 표준 에러 (stderr) 메시지
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);
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