What is the 7-step framework for cracking any coding interview?

Answer:

Most candidates fail coding interviews not because they can't code, but because they lack a structured thinking process. They panic and start writing code immediately — that's the fastest way to get rejected.

Here is the framework top candidates use:

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Step 1 — Clarify the Requirements

Never assume you understand the problem. Ask questions first:

• What is the input type and expected output?
• Are there constraints on time or space?
• Can the input be empty? Negative numbers? Duplicates?

The interviewer wants you to ask. It shows you think before you code.

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Step 2 — Restate the Problem in Your Own Words

Say it back to the interviewer before touching the keyboard.

"So if I understand correctly, I need to find the longest substring without repeating characters and return its length."

This catches misunderstandings early and proves you actually understand what you're solving.

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Step 3 — Start with Brute Force

Don't try to be clever yet. Describe the simplest, most obvious solution first — even if it's O(n²).

"My first thought is to check every possible pair using nested loops. It works, but it's slow."

This proves you can solve the problem and gives you a foundation to improve upon.

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Step 4 — Optimize with Patterns

This is where practice pays off. Ask yourself:

• Can I trade space for time with a hash map?
• Is there a two-pointer technique?
• Would a sliding window help?
• Can I sort first to simplify?

Say your reasoning out loud:

"If I use a hash map to store values I've seen, I can check in O(1) instead of scanning the whole array."

The interviewer is watching your reasoning, not just your final answer.

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Step 5 — Think Through Edge Cases

Before writing any code, list the tricky inputs:

• Empty array
• Single element
• All duplicates
• Negative numbers
• Maximum integer values

This shows the interviewer you write robust code, not just code that works on the happy path.

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Step 6 — State the Complexity

Before coding, tell the interviewer your time and space complexity.

"This runs in O(n) time and O(n) space because of the hash map."

If you can't analyze your own solution, that's a red flag.

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Step 7 — Write Clean Code

Now, and only now, do you write code:

• Use meaningful variable names
• Write helper functions where appropriate
• Handle edge cases first
• Walk through each line as you write it
• Trace through your code with a test case when done

Code Example:

// Example: Longest substring without repeating characters
func lengthOfLongestSubstring(_ s: String) -> Int {
    var charIndex = [Character: Int]()
    var maxLength = 0
    var left = 0
    let chars = Array(s)

    for right in 0..<chars.count {
        // Edge case: duplicate found — move left pointer
        if let prevIndex = charIndex[chars[right]], prevIndex >= left {
            left = prevIndex + 1
        }
        charIndex[chars[right]] = right
        maxLength = max(maxLength, right - left + 1)
    }

    return maxLength
}
// Time: O(n) | Space: O(n)

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Summary

Step	Action
1	Clarify requirements
2	Restate the problem
3	Brute force first
4	Optimize with patterns
5	Think through edge cases
6	State time & space complexity
7	Write clean, traced code

Remember: The interview is not about the answer. It's about how you think. Think first. Code second.

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