[LeetCode] Best Time to Buy and Sell Stock

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

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        int low = INT_MAX, profit = 0;
        for (int price : prices) {
            low = min(low, price);
            profit = max(profit, price - low);
        }
        return profit;
    }
};

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 :-)