> For the complete documentation index, see [llms.txt](https://docs-57.gitbook.io/data-structure-and-algorithms/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-57.gitbook.io/data-structure-and-algorithms/problems/greedy/best-time-to-buy-and-sell-stock.md).

# 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.

```csharp
public class Solution {
    public int MaxProfit(int[] prices) {
        
        if(prices.Length<=1){
            return 0;
        }
        int max_profit=0;
        int min_buy_cost=prices[0];
        for(int i=1; i<prices.Length;i++){
            
             // sell the stock now
            max_profit = Math.Max(max_profit,prices[i]-min_buy_cost);
            
            // buy the stock now
            min_buy_cost = Math.Min(min_buy_cost,prices[i]);
        }
        return max_profit;
    }
}
```