DSA · Greedy / one pass · #22

Best Time to Buy and Sell Stock

Module 25 · difficulty 1/5·⏱ 30:00starts on first keystroke

You are given an array `prices` where `prices[i]` is the price of a given stock on day `i`. Maximize profit by choosing a single day to buy and a later day to sell. Return the maximum profit; if no profit is possible, return `0`.

Examples

prices = [7,1,5,3,6,4] → 5 — buy at 1, sell at 6
prices = [7,6,4,3,1] → 0 — prices only fall
prices = [2,4,1] → 2

Stuck? Reveal an animated walkthrough of the approach.

Constraints

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

Session phases

A · Clarify

B · Approach

C · Complexity

D · Edges

E · Code

F · Tradeoff

G · Score

Phase A — Clarify

Ask questions about input bounds, types, and edge constraints.

Ask the coach clarifying questions about the problem.

When you've covered this phase, advance to the next.