Best Time to Buy and Sell Stock (One Transaction)

Given an integer array prices, where prices[i] is the stock price on day i, make at most one transaction: buy on one day and sell on a later day. Return the maximum profit possible. Return 0 if no profitable transaction exists. Input Line 1: integer n Line 2: n integers representing prices Output One integer: the maximum profit. Constraints 1 <= n <= 2 * 10^5 0 <= prices[i] <= 10^9 Example Input 6 7 1 5 3 6 4 Output 5