Best Time to Buy and Sell Stock
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 (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.
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. Selling on day 3 for profit 5 - 1 = 4 is less optimal.
Example 2
Input: prices = [7,6,4,3,1]
Output: 0
Explanation: Prices are strictly decreasing, so no profitable transaction is possible. Return 0.
Constraints
- -1 <= prices.length <= 10^5
- -0 <= prices[i] <= 10^4
Optimal Complexity
Time
O(n)
Space
O(1)
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