Best Time to Buy and Sell Stock
Difficulty: Easy
Category: DSA
Topics: Array, Dynamic Programming
Asked at: Amazon, Microsoft, Facebook, Apple, Adobe, Google, tcs, Bloomberg, eBay, Uber, ByteDance, Goldman Sachs, Expedia, VMware, Yahoo, Qualtrics, Oracle, ServiceNow, Visa, Samsung
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.
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**Example 2:**
**Input:** prices = [7,6,4,3,1]
**Output:** 0
**Explanation:** In this case, no transactions are done and the max profit = 0.
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**Constraints:**
- `1 <= prices.length <= 105`
- `0 <= prices[i] <= 104`