Best Time to Buy and Sell Stock

EasyArraysGreedy

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

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Problem

You are given an array prices where prices[i] is the price of a given stock on the ith day. You want to maximize your profit by choosing a **single day** to buy one stock and choosing a **different day in the future** to sell that stock. Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0.

Examples

Input: prices = [7,1,5,3,6,4]
Output: 5
Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6-1 = 5.
Input: prices = [7,6,4,3,1]
Output: 0
In this case, no transactions are done and the max profit = 0.

Constraints

  • 1 <= prices.length <= 10^5
  • 0 <= prices[i] <= 10^4

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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