Given an array prices where prices[i] is the price of a given stock on the ith day, find the maximum profit you can achieve by choosing a single day to buy and a single later day to sell.
Return the maximum profit. If no profit can be made, return 0.
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 transactions are done and the max profit = 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.
1 <= prices.length <= 10^50 <= prices[i] <= 10^4