class Solution {
public:
    int maxProfit(vector<int>& prices) {
        
        int min_p = INT_MAX, max_pf = 0, curr_pf = 0;
 
        for(int day = 0; day < prices.size(); day++){
 
            //finding min price so far
            if(prices[day] < min_p)
                min_p = prices[day];
 
            //if curr_pf == prices[day] - min_p > max_pf
            //update max_pf
            curr_pf = prices[day] - min_p;
 
            if(curr_pf > max_pf){
                max_pf = curr_pf;
            }
        }
 
        return max_pf;
    }
};

class Solution {
public:
    int maxProfit(vector<int>& prices) {
        
        int buy_day = 0;
        int curr_pf = 0, max_pf = 0;
 
        for(int curr_day = 0; curr_day < prices.size(); curr_day++){
            if(prices[curr_day] < prices[buy_day])
                buy_day = curr_day;
 
            curr_pf = prices[curr_day] - prices[buy_day];
 
            if(curr_pf > max_pf)
                max_pf = curr_pf;
        }
 
        return max_pf;
    }
};