Fibonacci Sequence
Source Code
#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long LL;
typedef pair<int, int> pii;
typedef pair<LL, LL> pll;
typedef pair<string, string> pss;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vii;
typedef vector<LL> vl;
typedef vector<vl> vvl;
typedef queue<int> qi;
typedef queue<char> qc;
typedef stack<int> si;
typedef stack<char> sc;
typedef map<LL, LL> mll;
#define F first
#define S second
#define PB push_back
//10000000000000000000
mll m;
LL mod = 1000000007;
LL fibo(LL n) {
if(m.count(n)) return m[n];
if(n % 2 == 0){
m[n] = (fibo(n / 2) * fibo((n / 2)) + fibo((n / 2) - 1) * fibo((n / 2)-1)) % mod;
}else{
m[n] = (fibo(n / 2)*fibo((n / 2) + 1) + fibo((n / 2) - 1) * fibo((n / 2))) % mod;
}
return m[n];
}
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
LL in;
cin >> in;
in--;
m[0] = 1;
m[1] = 1;
cout << fibo(in);
return 0;
}