Best Time to Buy and Sell Stock II
Difficulty: Medium
Category: DSA
Topics: Array, Dynamic Programming, Greedy
Asked at: Amazon, Apple, tcs, Microsoft, Facebook, Uber
You are given an integer array `prices` where `prices[i]` is the price of a given stock on the `ith` day.
On each day, you may decide to buy and/or sell the stock. You can only hold **at most one** share of the stock at any time. However, you can buy it then immediately sell it on the **same day**.
Find and return _the **maximum** profit you can achieve_.
**Example 1:**
**Input:** prices = [7,1,5,3,6,4]
**Output:** 7
**Explanation:** Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
Total profit is 4 + 3 = 7.
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**Example 2:**
**Input:** prices = [1,2,3,4,5]
**Output:** 4
**Explanation:** Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
Total profit is 4.
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**Example 3:**
**Input:** prices = [7,6,4,3,1]
**Output:** 0
**Explanation:** There is no way to make a positive profit, so we never buy the stock to achieve the maximum profit of 0.
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**Constraints:**
- `1 <= prices.length <= 3 * 104`
- `0 <= prices[i] <= 104`