Compute max profit from one stock trade
Company: Flipster
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Technical Screen
Given an integer array `prices` where `prices[i]` is the stock price on day `i`, compute the **maximum profit** you can achieve by choosing **at most one** day to buy and a later day to sell.
- You may complete **0 or 1** transaction.
- You must buy before you sell.
### Input
- `prices`: array of integers, `n >= 1`
### Output
- Maximum possible profit (integer).
### Example
- Input: `[7, 1, 5, 3, 6, 4]`
- Output: `5` (buy at 1, sell at 6)
### Edge cases
- Prices always decreasing → return `0`.
Quick Answer: This question evaluates a candidate's understanding of array-based data processing, difference maximization, and basic algorithmic optimization for time-series inputs. It is commonly asked in Coding & Algorithms interviews to assess fundamental practical programming ability and attention to edge cases (e.g.
Return the maximum profit from at most one buy followed by one later sell. Return 0 if no profitable trade exists.
Constraints
- n >= 1 in normal inputs
Examples
Input: ([7, 1, 5, 3, 6, 4],)
Expected Output: 5
Input: ([7, 6, 4, 3, 1],)
Expected Output: 0
Input: ([1],)
Expected Output: 0
Hints
- Track the minimum price seen so far.