121. 买卖股票的最佳时机

 public int maxProfit(int[] prices) {
        //前面交易日最小价格
        int minPrice=prices[0];
        //当前的最大收益
        int maxProfit=0;

        for (int i = 1,len=prices.length; i <len ; i++) {
            int currProfit=prices[i]-minPrice;
            if (currProfit>maxProfit){
                maxProfit=currProfit;
            }

            minPrice=minPrice>prices[i]?prices[i]:minPrice;
        }

        return maxProfit;
    }