Just a few days ago, one of our clients successfully passed a technical interview at TikTok. On the surface, the interview question seemed straightforward—almost deceptively so—but beneath that simple appearance was a deeply layered assessment. Without our real-time assistance service, the candidate might have been misjudged as “not strong enough” due to nerves, unclear explanations, or an overlooked edge case.

Let’s walk through the full experience of this interview, and show how CSOAHELP’s real-time assistance—through complete answer prompts and live code suggestions—helped the candidate turn the tide and walk out confidently.

Here’s the question:

Given a balanced parentheses string s, return the score of the string.
The score of a balanced parentheses string is based on the following rules:

• "()" has a score of 1
• AB has a score of A + B, where A and B are balanced strings
• (A) has a score of 2 * A, where A is a balanced string

Looks easy, right? That’s exactly what the candidate thought. He started with a classic solution: use a stack, push when encountering a (, and pop when encountering a ). If the popped value is (), add 1; if it’s a nested structure, multiply by 2.

Halfway into writing the code, the interviewer asked: “How does this hold up when the nesting gets really deep? Can you optimize it to linear time?”

That single follow-up froze the candidate for a few seconds. He wasn’t sure how to pivot the answer on the spot.

This is when CSOAHELP’s real-time assistant kicked in, pushing a full-text prompt to his secondary device:

“A more optimized solution would use a numeric stack. Push 0 whenever you see '('. When you see ')', pop from the stack. If it’s 0, that means it’s '()', and the score is 1. If it's a number, multiply it by 2 and add it to the previous layer. This approach requires only one linear pass—O(n) time and O(n) space.”

The candidate picked it up and started speaking naturally: “There’s actually a more efficient way using a numeric stack. We push 0 when we encounter '(', acting as a placeholder for the current score. When we hit ')', if the top is 0, that means we saw '()', which is worth 1 point. If the top is a number, that’s the score of a nested structure, so we multiply it by 2 and add it back to the previous stack frame. This only needs one pass through the string, so it’s O(n) time.”

The interviewer nodded. “That’s a good explanation. What about handling cases with mixed nesting and multiple segments?”

This is where many candidates start spiraling. But with CSOAHELP still in the background, another prompt appeared with the follow-up response:

“This approach works well for mixed structures like (()(())), because each level is isolated in the stack and can accumulate and bubble up correctly—stack naturally supports both nesting and concatenation.”

The candidate echoed that confidently: “This stack-based method handles both nesting and consecutive segments naturally. For instance, with (()(())), each pair accumulates its own score and gets added back to the upper layer, ensuring nothing gets misaligned or double-counted.”

The interviewer seemed pleased, but followed up with: “Can you implement it in code?”

At this point, the candidate was a bit anxious—unsure where to start and worried about writing incorrect syntax under pressure.

CSOAHELP instantly pushed a working code snippet to his screen—succinct, clean, and structured for easy reading and explanation:

def scoreOfParentheses(s: str) -> int:
    stack = [0]
    for c in s:
        if c == '(':
            stack.append(0)
        else:
            v = stack.pop()
            stack[-1] += max(2 * v, 1)
    return stack[0]

The candidate typed it out and began walking through the code, explaining the variable logic, control flow, and why the stack starts with a 0. His flow was confident and his logic clear. The interviewer visibly relaxed and complimented him: “This implementation is clean, and you explained it really well. Most candidates get confused by this point.”

The interview ended on that high note, and not long after, the candidate received an invitation to move forward to the next round.

So why was this question so tricky? Because it’s the perfect example of a “deceptively simple” interview challenge. Many candidates get the general idea, but fall apart during follow-ups. You get the code right, but can't articulate the logic. You understand the problem, but sound like you're guessing. Or worse, you’re actually right—but can't make the interviewer feel that you are.

This type of question is exactly what TikTok, Google, Stripe, and other top-tier companies love: easy to explain, hard to master, and excellent for digging deep into a candidate’s reasoning under pressure. These interviews aren’t just checking whether your code runs—they’re evaluating how clearly, logically, and confidently you can explain a robust, production-grade solution.

This particular interview is one of CSOAHELP’s most representative success cases. Our real-time assistance didn’t just offer vague suggestions—it delivered complete sentence-by-sentence explanations the candidate could confidently speak, along with copy-friendly code blocks that could be typed directly without second-guessing.

We had already prepared three solution approaches ahead of time—recursive, stack-based, and counting—for multiple possible directions the interview could go. Each version came with its own clear explanation template, performance analysis, and code sample. All the candidate had to do was follow the guidance, read or paraphrase the provided text, and write or recite the code when prompted.

He didn’t have to worry about edge cases—we had prepped explanations for all of them.
He didn’t need to stress over how to structure his answer—we had done that in advance.
He didn’t need to panic during follow-ups—we were there, feeding him the next logical step.

Real interviews don’t offer a second chance. The first sentence you say sets the tone. The first code you write sets the impression. You may be talented—but it’s your performance that counts.

CSOAHELP doesn’t replace your skills—it reveals them. We help you express clearly what you already know, stay calm under pressure, and deliver your answers like a pro. If you’re preparing for interviews at TikTok, Google, Apple, Stripe, or any other high-pressure tech role, even a single session with us—whether it’s live support or mock practice—could make the difference between an almost-offer and a real one.

This isn’t cheating. It’s not trickery. It’s clarity, structure, and composure—delivered at the moment you need them most. You write code—we help you explain it. You solve problems—we help you say it right. You’re capable—we make sure that shows.

CSOAHELP: Real-Time Interview Assistance. Helping you turn every opportunity into success—when it matters most.

经过csoahelp的面试辅助，候选人获取了良好的面试表现。如果您需要面试辅助或面试代面服务，帮助您进入梦想中的大厂，请随时联系我。

If you need more interview support or interview proxy practice, feel free to contact us. We offer comprehensive interview support services to help you successfully land a job at your dream company.