122. Best Time to Buy and Sell Stock II

You may complete as many transactions as you like
So the result is the sum of all profitable transactions.
99.90 %
class Solution {
    public int maxProfit(int[] prices) {
        if (prices == null || prices.length == 0) {
            return 0;
        }
        int sum = 0;
        int diff = 0;
        for (int i = 0; i < prices.length - 1; i++) {
            diff = prices[i + 1] - prices[i];
            if (diff > 0) {
                sum += diff;
            }
        }
        return sum;
    }
}