121. best time to buy and sell stock

class Solution {
    public int maxProfit(int[] prices) {
        if (prices.length==0){
            return 0;
        }
        int min = prices[0]; 
        int max = 0;
        for(int price : prices ){
            if (price-min>max){
                max = price-min;
            }
            if (price<min){
                min = price;
            }
        }
        return max;
    }
}