#121

Best Time to Buy and Sell Stock

Easy
ArrayDP

You are given an array `prices` where `prices[i]` is the price of a given stock on the `i`th 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`.

Examples

Example 1
Input: prices = [7,1,5,3,6,4]
Output: 5
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
In this case, no transactions are done and the max profit = 0.

Constraints

  • 1 <= prices.length <= 10^5
  • 0 <= prices[i] <= 10^4
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