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# Best Time to Buy and Sell Stock

Updated: Mar 24, 2021

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.

```

Constraints:

• 1 <= prices.length <= 105

• 0 <= prices[i] <= 104

Solution:

```class Solution {
public int maxProfit(int[] prices) {
int minprice = prices;
int maxprofit=0;
for(int i=0;i<prices.length;i++)
{
if(prices[i]<minprice) minprice=prices[i];
else if((prices[i]-minprice)>maxprofit)
{
maxprofit = prices[i]-minprice;
}
}
return maxprofit;
}
}

```

Approach 2:

```class Solution
{
public int maxProfit(int[] prices)
{
int havingstock,nothavingstock;
havingstock = -prices;
nothavingstock =0;

for(int i=1;i<prices.length;i++)
{
havingstock = Math.max(havingstock,-prices[i]);
nothavingstock = Math.max(nothavingstock,havingstock+prices[i]);
}
return nothavingstock;
}
}

```