# 122. Best Time to Buy and Sell Stock II

## 題目概要

給定一個整數陣列 prices，其中 prices[i] 是當天股票的價格。每一天你都可以決定買入或賣出股票。在任何時候最多只能持有一股股票。可以在同一天買入和賣出。

請輸出最大利潤。

Example 1:

Input: prices = [7,1,5,3,6,4]
Output: 7
Explanation: Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
Total profit is 4 + 3 = 7.

Example 2:

Input: prices = [1,2,3,4,5]
Output: 4
Explanation: Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
Total profit is 4.

Example 3:

Input: prices = [7,6,4,3,1]
Output: 0
Explanation: There is no way to make a positive profit, so we never buy the stock to achieve the maximum profit of 0.

## 解題技巧

- 如果 `prices[i - 1] < prices[i]`就代表可以獲取利潤，利潤為 `prices[i] - prices[i - 1]`

## 程式碼

/**
 * @param {number[]} prices
 * @return {number}
 */
var maxProfit = function(prices) {
	let profit = 0
	for (let i = 1; i < prices.length; i++) {
		if (prices[i - 1] < prices[i]) {
			profit += (prices[i] - prices[i - 1]);
		}
	}

	return profit;
};