122. Best Time to Buy and Sell Stock II

Say you have an array for which the ith element is the price of a given stock on day i.

Design an algorithm to find the maximum profit. You may complete as many transactions as you like (ie, buy one and sell one share of the stock multiple times). However, you may not engage in multiple transactions at the same time (ie, you must sell the stock before you buy again).

public class Solution {
    public int maxProfit(int[] prices) {
/*        if (prices == null || prices.length == 0 || prices.length == 1) {
            return 0;
        }
        int profit = 0;
        int min = prices[0];
        boolean up = false; // Need to have a tag for tracking the trend.
        for (int i = 1; i < prices.length; i++) {
            if (prices[i] >= prices[i - 1]) {
                up = true;
                continue;
            } else {
                if (up = true) {
                    profit += prices[i - 1] - min;
                }
                up = false;
                min = prices[i];
            }
        }
        // The original orgorithm can not continue to add value to profit if the last price is higher.
        if (up) {
            profit += prices[prices.length - 1] - min;
        }
        return profit;
*/
        int profit = 0;
        int dif = 0;
        for (int i = 0; i < prices.length - 1; i++) {
            dif = prices[i + 1] - prices[i];
            if (dif > 0) {
                profit += dif;
            }
        }
        return profit;
    }
}
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