Practice/Meta/Leetcode 121. Best Time to Buy and Sell Stock

Leetcode 121. Best Time to Buy and Sell Stock

CodingMust

Problem

You are given an array representing the daily prices of a stock over a period of time. Each element in the array corresponds to the stock's price on a specific day.

Your goal is to determine the maximum profit you can achieve by completing at most one transaction. A transaction consists of buying the stock on one day and selling it on a strictly later day.

If no profitable transaction is possible, return 0.

Requirements

1. You must buy before you sell (you cannot sell before buying)
2. You can complete at most one buy-sell pair
3. Return the maximum profit possible, or 0 if no profit can be made
4. The solution should handle arrays of any length including edge cases

Constraints

• 1 <= prices.length <= 100,000
• 0 <= prices[i] <= 10,000
• Time complexity should be O(n) or better
• Space complexity should be O(1)

Examples

Example 1:

Input: prices = [7, 1, 5, 3, 6, 4] Output: 5 Explanation: Buy on day 2 (price = 1) and sell on day 5 (price = 6), profit = 6 - 1 = 5. Note that buying on day 2 and selling on day 1 is not allowed because you must buy before you sell.

Example 2:

Input: prices = [7, 6, 4, 3, 1] Output: 0 Explanation: In this case, no profitable transactions can be made, so the maximum profit is 0.

Example 3:

Input: prices = [2, 4, 1] Output: 2 Explanation: Buy on day 1 (price = 2) and sell on day 2 (price = 4), profit = 4 - 2 = 2.