Google onsite made me doubt my capabilities as a programmer

So yesterday I had my first onsite for Google. My interviewer arrived 15 minutes late and disconnected a couple of times due to a bad connection, but that’s not important. When he pasted the problem,

So yesterday I had my first onsite for Google. My interviewer arrived 15 minutes late and disconnected a couple of times due to a bad connection, but that’s not important. When he pasted the problem, I immediately knew I wouldn’t be able to solve it optimally. (It was this exact problem, call me a loser, but problems that require mathematical intuitions like these have never really clicked for me.) So I decided to go with a brute-force approach. I then spent 40 minutes implementing a fucking simple two nested loop brute-force solution, with him helping me. I’ve done around 400 LeetCode problems, I’ve published successful side projects, and I’ve been working as a software engineer for two years now, normally I'm sure I could have done it in 10 minutes top. And yet, by the end of the interview, after taking 40 minutes to implement a brute-force solution I started wondering whether I’m even fit for this career. Has this level of fucking up ever happened to you?