[코테] 리트코드 배열 121. Best Time to Buy and Sell Stock

121. Best Time to Buy and Sell Stock

문제 링크

https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/

문제 설명

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.

제한 사항

• 1 <= prices.length <= 105
• 0 <= prices[i] <= 104

입출력 예 #1

1. Input: prices = [7,1,5,3,6,4]
2. Output: 5
3. 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.

입출력 예 #2

1. Input: prices = [7,6,4,3,1]
2. Output: 0
3. Explanation: In this case, no transactions are done and the max profit = 0.

문제 풀이

리스트를 순회하면서 최솟값과 최대이득을 갱신하여 마지막에 나온 최대이득을 리턴한다.

class Solution:
    def maxProfit(self, prices: List[int]) -> int:
        profit = 0
        min_price = sys.maxsize

        # 최솟값과 최댓값을 계속 갱신
        for price in prices:
            min_price = min(min_price, price)
            profit = max(profit, price - min_price)

        return profit