121 Best Time to Buy and Sell Stock

这题是看算法导论学会的。。。。

public class Solution {    public int maxProfit(int[] prices) {        if (prices == null || prices.length <= 1) {            return 0;        }        int max = Integer.MIN_VALUE;        int sum = 0;        for (int i = 1; i < prices.length; i++) {            int profit = prices[i] - prices[i - 1];            sum += profit;            if (sum < 0) {                sum = 0;            }            max = Math.max(max, sum);        }        return max;    }}