How to BUY and SELL Bitcoin？

Posted 2023-04-01 区块链文博

Buying and selling Bitcoin involves a few basic steps:

1.Choose a cryptocurrency exchange: There are many cryptocurrency exchanges available, such as Coinbase, Binance, Kraken, and Bitstamp. Research and choose one that suits your needs, and create an account.
2.Verify your identity: Most reputable exchanges require you to verify your identity before you can buy or sell Bitcoin. This typically involves providing personal information and submitting a government-issued ID.
3.Fund your account: You can fund your account with fiat currency, such as US dollars or Euros, using a bank transfer, credit card, or debit card. Some exchanges also allow you to fund your account with other cryptocurrencies.
4.Buy or sell Bitcoin: Once your account is funded, you can buy or sell Bitcoin on the exchange’s trading platform. This typically involves placing an order to buy or sell Bitcoin at a certain price.
5.Store your Bitcoin: After buying Bitcoin, you should store it in a secure digital wallet. Some exchanges offer their own wallet services, but it’s generally recommended to use a separate wallet that you control.

Here are some additional tips to keep in mind:

Be aware of the risks: Cryptocurrency prices can be volatile, and there is always the risk of losing money. Make sure you understand the risks involved before investing.
Keep your private keys secure: Your private keys are used to access your Bitcoin, so it’s important to keep them secure. Use a reputable wallet and take precautions to protect your keys from theft or loss.
Consider the tax implications: In many countries, cryptocurrency transactions are subject to taxation. Consult a tax professional to understand the tax implications of buying and selling Bitcoin in your jurisdiction.

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算法分析与设计第一周121.Best Time to Buy and Sell Stock&122. Best Time to Buy and Sell Stock II

原题来自：121：https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/

122：https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/description/

第一周，小试牛刀吧。

题目121不复杂，就是英文原题读起来怪怪的。意思是，在保证先买后卖且最多只能买卖一次的情况下，计算最大利润。

思路很简单：逐个求差，差最大且被减数的下标大于减数的下标就可以了。最简单暴力的方法是用两重循环：

int maxProfit(int* prices, int pricesSize) {
    int max = 0;
    for (int i = 0; i < pricesSize; i++) {
        for (int j = i; j < pricesSize; j++) {
            if (prices[j] - prices[i] > max) {
                max = prices[j] - prices[i];
                }
    }
    }
    return max;
}

 

 

显然，此算法的时间复杂度为0（n^2）。根据leetcode给出的分析图，虽然AC，我的方法还有很大的优化空间。

优化的话，思路本质上还是一样的。就是求一个峰值和谷底值之差，且峰值在谷底值后面。主要是能否想到一个巧妙的方法避开双重循环，目前还没想好。

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做完121，发现还有升级版122。122的意思是，在保证先买后卖且在一个买卖周期内最多只能买卖一次的情况下，计算最大利润。也就是说，卖出之后还可以再进行买入等操作。

这就很有意思了。在没有买卖次数限制的情况下，同样是获得最大利润，情况可以有多种。一开始我是懵的。第一反应是穷举，计算出所有能盈利的情况，再进行比较，得到最大利润。先不说这是个比较浩大的工程量，最重要的是我根本不知道这看似简单的方法从何下手(ˉ▽ˉ；)...。

后来观摩了一下讨论区，发现一位大牛的做法很有意思。大牛的思路很巧妙，就是逐个相减，差大于零就盈利，把盈利的部分加起来；差小于零就进入往后挪，继续相减。哇，简直神奇！把n天切割成n次买卖，每次在第i天买入，第i+1天卖出。只看上升的小段，叠加，忽略下降的小段。

举个简单的例子。对于一种情况{4, 1, 2, 3, 5}来说，最佳盈利策略应当是在1的时候买入，5的时候卖出，盈利为4，一手买卖即可。而按照上面的方法，将这一手买卖分解为1买2卖，2买3卖，3买5卖，共盈利4，三次买卖利润与前面的一手买卖利润一致，但是解释起来更加简便、清晰。

对于另一种情况{4, 1, 3, 2, 5}来说，两个峰，只看上升的小段，看起来就更加清楚了。

 

这种方法就相当于把长线买卖都简化成了“如果保证盈利，买了马上就卖”的小短线模式的叠加，与周五刚刚学过的“分治”思想还真有异曲同工之妙。

代码实现起来就很简单了：

int maxProfit(int* prices, int pricesSize) {
    int total = 0;
    for (int i=0; i< pricesSize-1; i++) {
        if (prices[i+1] > prices[i]) total += prices[i+1] - prices[i];
    }
    return total;
}