How to Explain a LeetCode Solution in English

The five-step spoken script

1. 1. Restate

   Say the problem in your own words.

   One or two sentences. Show you understood the input, the output, and the goal — not that you memorised the prompt.

2. 2. Approach

   Name the method before you code.

   Brute force first if you need it, then the structure you will use: hash map, two pointers, stack, binary search.

3. 3. Example

   Walk one concrete input.

   Pick small numbers. Say what you store, what you compare, and what you return. Interviewers follow an example more easily than abstract talk.

4. 4. Time and space

   One sentence each.

   After the example, before you claim you are done. “Time is O(n) because we scan once. Space is O(n) for the map.”

5. 5. Edge cases

   Name at least one unusual input.

   Empty input, duplicates, already sorted, overflow. Invite a follow-up: “I would also check …”

Practise a problem

Pick a classic problem, record 60–90 seconds, and get a scorecard on that script. You do not need to write code.

• Easy

  Two Sum

  Two Sum is the classic “hash map while you scan” problem. Say the brute-force pair check first, then the map, walk [2, 7, 11, 15] with target 9, and finish with O(n) time and the empty-array case.

• Easy

  Valid Parentheses

  Valid Parentheses is a stack story. Say you push opening brackets, pop when a closer matches, and fail if the stack is empty too soon or not empty at the end.

• Easy

  Binary Search

  Binary search is a “sorted, so I can discard half” story. Say left and right, compare the mid, and keep the half that can still contain the target.

• Easy

  Detect duplicates

  This is the course prompt: detect duplicate customer records. Pick a key (email), name a hash set or a GROUP BY, walk one example, then say what you would do when names almost match.