https://leetcode.com/problems/sum-of-two-integers/ 문제 > You are given an array prices where prices[i] is the price of a given stock on the ith 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 from this transaction. If you cannot achieve any profit, return 0. Example 1: > Input: prices = [7,1,5,3,6,4] Output: 5 Explanation: Buy on day 2 (pri