Day 38

Que: https://leetcode.com/problems/best-time-to-buy-and-sell-stock/submissions/837463568/

case 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.

Case 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


class Solution {
public:
    int maxProfit(vector<int>& prices) {
        if(prices.size() == 0) return 0;
        
        int ans = 0;
        
        int start = prices[0], end = prices[0];
        
        for(int i = 0; i < prices.size(); i++){
            if(prices[i] < start){
                //restart as session
                ans = max(ans, end - start);
                start = prices[i];
                end = prices[i];
            }else{
                //continue current session
                end = max(end, prices[i]);
            }
        }
        ans = max(ans, end - start);
        return ans;
        
    }
};