Free AI LeetCode Communication Coach — Daily Temperatures

The problem

Given temperatures[i], return an array answer where answer[i] is the number of days you wait until a warmer temperature. If none, 0.

Example: temperatures = [73,74,75,71,69,72,76,73] → [1,1,4,2,1,1,0,0]

Monotonic stack — say indices, not values.

ans = [0] * len(temperatures)
stack = []
for i, t in enumerate(temperatures):
    while stack and temperatures[stack[-1]] < t:
        j = stack.pop()
        ans[j] = i - j
    stack.append(i)
return ans

How to explain it

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 …”

• “I keep a decreasing stack of indices.”
• “Each index is pushed and popped at most once.”

Practise out loud

1. 1. Restate

   For each day I need how many days until a strictly warmer temperature, or zero.

2. 2. Approach

   I keep a monotonic stack of indices with decreasing temperatures. When today is warmer, I pop and fill the wait.

3. 3. Example

   On 73 then 74, the wait for day 0 is 1. Later 76 resolves several cooler days at once.

4. 4. Time and space

   Time is O(n) because each index is pushed and popped at most once. Space is O(n).

5. 5. Edge cases

   I would check a strictly decreasing list — all zeros — and a single-day input.

Common mistakes when explaining Daily Temperatures

• Storing values instead of indices on the stack.
• Not saying each index is pushed and popped at most once.