<p>You are given an integer array <code>prices</code> where <code>prices[i]</code> is the price of a given stock on the <code>i<sup>th</sup></code> day.</p>

<p>On each day, you may decide to buy and/or sell the stock. You can only hold <strong>at most one</strong> share of the stock at any time. However, you can buy it then immediately sell it on the <strong>same day</strong>.</p>

<p>Find and return <em>the <strong>maximum</strong> profit you can achieve</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> prices = [7,1,5,3,6,4]
<strong>Output:</strong> 7
<strong>Explanation:</strong> 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.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> prices = [1,2,3,4,5]
<strong>Output:</strong> 4
<strong>Explanation:</strong> Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
Total profit is 4.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> prices = [7,6,4,3,1]
<strong>Output:</strong> 0
<strong>Explanation:</strong> There is no way to make a positive profit, so we never buy the stock to achieve the maximum profit of 0.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= prices.length &lt;= 3 * 10<sup>4</sup></code></li>
	<li><code>0 &lt;= prices[i] &lt;= 10<sup>4</sup></code></li>
</ul>

class Solution {
public:
    int pro(vector<int>& prices, int n, int index) {
        if (index >= n) {
            return 0;
        }
        
        int buy = prices[index];
        int sell = 0;
       
        int profit = 0;

        if (index + 1 < n && prices[index + 1] > buy) {
            sell = prices[index + 1];
            index+1;
             profit = sell - buy; 
        } 
        profit = profit+ pro(prices, n, index + 1);  

        return profit;
    }

    int maxProfit(vector<int>& prices) {
        return pro(prices, prices.size(), 0);
    }
};


// class Solution {
// public:
//     int maxProfit(vector<int>& prices) {
//         int r=1,l=0,max=0;
//         while(r<prices.size())
//         {
//             if(prices[r]<prices[l])
//             {
//                 l=r;
//                 r++;
//             }
//             else
//             {
//                 if(prices[r+1]<=prices[r])
//                 {
//                     max+=prices[r]-prices[l];
//                     l=r+1;
//                     r+=2;
//                     continue;
//                 }
//                 else
//                 {
//                     while(prices[r+1]>prices[r])
//                     {
//                         r+=1;
//                     }
//                 }
//             }
//         }
//         return max;
//     }
// };
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