122. Best Time to Buy and Sell Stock II

    /*
     * 122. Best Time to Buy and Sell Stock II
     * 第二题，可以进行无限次，所以只要大于0的都加上
     */
    public int maxProfit2(int[] prices) {
        if (prices == null || prices.length == 0 || prices.length == 1)
            return 0;
        int res = 0;
        int low = prices[0];
        for (int i = 1; i < prices.length; i++) {
            if (prices[i] > low) {
                res = res + prices[i] - low;
            }
            low = prices[i];
        }
        return res;
    }