记录自己作为程序学习过程中,一些重点的学习资料,视频多为udemy或者其他平台

最近在项目中遇到了加密权重算法,记录下使用心得

• Given a list of items where each item has a weight (integer value), select a random item from the list based on that weight.
• The key requirement — items with a higher weight value are more likely to be returned. So even the lowest weighted value will still sometimes be returned from the function.

1.Add up all the weights for all the items in the list 2.Pick a number at random between 1 and the sum of the weights 3.Iterate over the items 4.For the current item, subtract the item’s weight from the random number that was originally picked 5.Compare the result to zero. If less than or equal to zero then break otherwise keep iterating. The key is that the larger the weight the more likely to be less than zero when compared to the random selection between zero and the sum of weights. 6.If not less than zero, continue iterating over the list, all the while subtracting more and more weights off the random number chosen from the sum of the weights.

在编码过程中,经常会遇到使用逻辑运算符的情况,其中对于溢出操作需要特别小心

1. 编译型语言，编译器的静态求值是自然的。
2. 必须使用强制类型转换。甚至于对一个uint16变量赋uint8的值都是不允许的。
3. 整数字面值不包含存储空间的大小，可以直接赋给各种uintX（必须不溢出）。
4. <<运算的结果的类型，以左侧操作数为准。

const c_i8 uint8 = 255
var i16 uint16
i16 = uint16(c_i8 << 4) // constant 4080 overflows uint8
i16 = uint16(uint8(255) << 4) // constant 4080 overflows uint8

因为<<左侧都是uint8，所以最终的结果也是uint8，则得出的结果装不下uint8就会报错，哪怕最后准备了uint16的容器也不行