Input: [7, 1, 5, 3, 6, 4]
Output: 5
max. difference = 6-1 = 5 (not 7-1 = 6, as selling price needs to be larger than buying price)
Input: [7, 6, 4, 3, 1]
Output: 0
In this case, no transaction is done, i.e. max profit = 0.

Already Pass Solution

    public int MaxProfit(int[] prices) {
        int result = 0;
        int curMax = 0;
        for(int i = 1; i < prices.Length; i++)
        {
            curMax += prices[i] - prices[i - 1];
            curMax = Math.Max(0, curMax);
            result = Math.Max(curMax,result);
        }
        return result;
    }

解题思路：
1.使用结合律获取最大差值

待思考：