Java#买卖股票的最佳时机

class Solution {
    public int maxProfit(int[] prices) {
        if(prices.length==0||prices.length==1){
            return 0;
        }
        int previous=prices[0];
        int sum=0;
        for(int i=0;iprevious){
                sum+=now-previous;
            }
            previous=prices[i];
        }
        return sum;
    }
}