// ~~ icebear ~~
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
template<class T>
bool minimize(T &a, const T &b) {
if (a > b) return a = b, true;
return false;
}
template<class T>
bool maximize(T &a, const T &b) {
if (a < b) return a = b, true;
return false;
}
#define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
#define FORR(i,a,b) for(int i=(a); i>=(b); --i)
#define REP(i, n) for(int i=0; i<(n); ++i)
#define RED(i, n) for(int i=(n)-1; i>=0; --i)
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define task "cuuho"
const int MOD = 1e9 + 7;
const int inf = 1e9 + 27092008;
const ll INF = 1e18 + 27092008;
const int N = 1e5 + 5;
const int S = 300;
int n, d[N], x[N], dp[N], pref[N][S + 5];
void init(void) {
cin >> n;
FOR(i, 1, n) cin >> d[i] >> x[i];
}
void process(void) {
dp[1] = 1;
FOR(i, 1, n) {
FOR(j, 1, S) if (i >= j) {
(pref[i][j] += pref[i - j][j]) %= MOD;
(dp[i] += pref[i][j]) %= MOD;
}
if (d[i] <= S && i + d[i] <= n) {
(pref[i][d[i]] += dp[i]) %= MOD;
ll e = i + 1LL * d[i] * (x[i] + 1);
if (e <= n) pref[e][d[i]] = (pref[e][d[i]] - dp[i] + MOD) % MOD;
} else {
FOR(j, 1, x[i]) {
if (i + j * d[i] > n) break;
(dp[i + j * d[i]] += dp[i]) %= MOD;
}
}
}
int ans = 0;
FOR(i, 1, n) (ans += dp[i]) %= MOD;
cout << ans;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int tc = 1;
// cin >> tc;
while(tc--) {
init();
process();
}
return 0;
}
컴파일 시 표준 에러 (stderr) 메시지
Main.cpp: In function 'int main()':
Main.cpp:74:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
74 | freopen(task".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:75:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
75 | freopen(task".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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