122 best time to buy and sell stock ii

122. 买卖股票的最佳时机 II

go：

func maxProfit(prices []int) int {
    earn := 0
    for i := 1; i < len(prices); i++ {
        diff := prices[i] - prices[i - 1]
        if diff > 0 {
            earn += diff
        }
    }

    return earn
}