In this post, we are going to solve the** 121. Best Time to Buy and Sell Stock** problem of Leetcode. This problem **121. Best Time to Buy and Sell Stock** is a Leetcode **easy **level problem. Let’s see code, **121. Best Time to Buy and Sell Stock** **– Leetcode Solution**.

**Problem**

You are given an array `prices`

where `prices[i]`

is the price of a given stock on the `i`

day.^{th}

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.
```

**Constraints**

`1 <= prices.length <= 10`

^{5}`0 <= prices[i] <= 10`

^{4}

Now, let’s see the code of **121. Best Time to Buy and Sell Stock** – Leetcode Solution.

**Best Time to Buy and Sell Stock – Leetcode Solution**

**121. Best Time to Buy and Sell Stock** – Solution in Java

**– Solution in Java**

**121. Best Time to Buy and Sell Stock**class Solution { public int maxProfit(int[] prices) { int minCostToBuyAt = prices[0]; int profit = 0; for(int i=1; i< prices.length; i++){ minCostToBuyAt = Math.min(minCostToBuyAt,prices[i]); profit = Math.max(profit,prices[i] - minCostToBuyAt); } return profit; } }

**121. Best Time to Buy and Sell Stock** – Solution in C++

**C++**

**– Solution in****121. Best Time to Buy and Sell Stock**class Solution { public: int maxProfit(vector<int>& prices) { int minCostToBuyAt = prices[0]; int profit = 0; for(int i=1; i< prices.size(); i++){ minCostToBuyAt = min(minCostToBuyAt,prices[i]); profit = max(profit,prices[i] - minCostToBuyAt); } return profit; } };

**121. Best Time to Buy and Sell Stock** **– Solution in **Python

**121. Best Time to Buy and Sell Stock**

**Python**

**– Solution in**class Solution: def maxProfit(self,prices): left = 0 #Buy right = 1 #Sell max_profit = 0 while right < len(prices): currentProfit = prices[right] - prices[left] if prices[left] < prices[right]: max_profit =max(currentProfit,max_profit) else: left = right right += 1 return max_profit

**Note:** This problem **121. Best Time to Buy and Sell Stock** is generated by **Leetcode **but the solution is provided by **CodingBroz**. This tutorial is only for **Educational** and **Learning** purpose.