CF 102644C - Fibonacci

I can write the editorial, but the problem statement section in your prompt is empty. I found that Codeforces 102644C “Fibonacci” asks for the n-th Fibonacci number modulo $10^9+7$, with $0 le n le 10^{18}$.

codeforcescompetitive-programming

CF 102644C - Fibonacci

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Solution

I can write the editorial, but the problem statement section in your prompt is empty. I found that Codeforces 102644C “Fibonacci” asks for the n-th Fibonacci number modulo $10^9+7$, with $0 \le n \le 10^{18}$.

Before producing the full editorial, I need one clarification: should I write the editorial for this exact problem (fast doubling / matrix exponentiation Fibonacci), or did you intend a different “Fibonacci” problem whose statement was omitted?