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 dayi.

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).

Brainstorm

Approach #1: Sell if the Next Price Point is Higher

int maxProfit(vector<int>& prices) {
    if (prices.size() == 0) return 0;
    int max_profit = 0;
    for (int i = 0; i < prices.size() - 1; i++) {
        if (prices[i+1] > prices[i]) max_profit += prices[i+1] - prices[i];
    }    
    return max_profit;
}

Time complexity: $$O(n)$$

In worst case, we consider all prices in the array.

Space complexity: $$O(1)$$