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  1. #include <iostream>
  2. using namespace std;
  3. typedef long long ll;
  4.  
  5. const ll MOD = 1e9 + 7;
  6.  
  7. ll fib(ll n) {
  8.     if (n == 0) return 0;
  9.     ll a = 0, b = 1;
  10.     for (ll i = 2; i <= n; ++i) {
  11.         ll temp = (a + b) % MOD;
  12.         a = b;
  13.         b = temp;
  14.     }
  15.     return b;
  16. }
  17.  
  18. int main() {
  19.     ll n;
  20.     cin >> n;
  21.     cout << fib(n) << endl;
  22.     return 0;
  23. }
  24.  
Success #stdin #stdout 3.51s 5304KB
comments (?)
stdin 
1000000000
stdout 
21
https://ideone.com/mGGwqu
language:
C++ (gcc 8.3)
created:
4 days ago
visibility:
public

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