Problem

You are given an array prices where prices[i] is the price of a given stock on the i-th 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. If you cannot achieve any profit, return 0.

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.

Example 2:

Input: prices = [7, 6, 4, 3, 1]
Output: 0

Explanation: In this case, no transactions are done and the max profit = 0.

Constraints

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