Best Time To Buy And Sell Stocks

class Solution {
	public:
		int maxProfit(vector<int>& prices) {
        
        int lsf = INT_MAX; // least so far
        int op = 0; // overall profit
        int pist = 0; // profit if sold today
        
        int len = prices.size();
        
        for(int i = 0; i < len; i ++) {
            
            if(prices[i] < lsf) {
                
                lsf = prices[i];
                
            }
            
            pist = prices[i] - lsf;
            
            if(op < pist) {
                op = pist;
            }
        }
        return op;
    }
};