shares a very simple solution, whose code is rewritten below, just 5 lines :-)

1 class Solution { 2 public: 3     int maxProfit(vector
     
      & prices) { 4         int low = INT_MAX, profit = 0; 5         for (int price : prices) { 6             low = min(low, price); 7             profit = max(profit, price - low); 8         } 9         return profit;10     }11 };
     

To give an explanation, suppose we denote p[n] to be the maximum profit we can earn from days 0 to n. Then we have the following DP recursive formula:

p[n + 1] = max(p[n], prices[n + 1] - min_{i = 0, ..., n}prices[i]).

The above code simply computes this formula :-)