UCB CS61A 题

请求高手帮帮忙， 把这题给刷了。  来在  UC B  HW08 的 题目

Question 7: Linear Congruential GeneratorA common method of producing pseudo-random numbers is by means of thefollowing recurrence relation:

• R0 = seed value
• Ri+1 = (a*Ri + c) % n  where Ri denotes the ith pseudo-random number in the  stream; a, c, and n are constant integers, and seed value is some  initial value provided by the user or chosen automatically by the system.
  

Define a function that returns a stream of random numbers that usesthis linear-congruential formula.
from operator import add, mul, moddef make_random_stream(seed, a, c, n):    """The infinite stream of pseudo-random numbers generated by the    recurrence r[0] = SEED, r[i+1] = (r * A + C) % N.  Your solution    must not use any lambdas or def's that we have not supplied in the    skeleton.    >>> s = make_random_stream(25, 29, 5, 32)    >>> stream_to_list(s, 10)    [25, 26, 23, 0, 5, 22, 3, 28, 17, 18]    >>> s = make_random_stream(17, 299317, 13, 2**20)    >>> stream_to_list(s, 10)    [17, 894098, 115783, 383424, 775373, 994174, 941859, 558412, 238793, 718506]    """    "*** YOUR CODE HERE ***"Your solution must use [i]only the functions defined in the skeleton, withoutdefining any additional ones.Likewise, any lambda expressions should contain only calls to thesefunctions.
Use OK to test your code:
python3 ok -q make_random_stream

感谢！

from operator import add, mul, moddef make_random_stream(seed, a, c, n):    """The infinite stream of pseudo-random numbers generated by the    recurrence r[0] = SEED, r[i+1] = (r[i] * A + C) % N.  Your solution    must not use any lambdas or def's that we have not supplied in the    skeleton.    >>> s = make_random_stream(25, 29, 5, 32)    >>> stream_to_list(s, 10)    [25, 26, 23, 0, 5, 22, 3, 28, 17, 18]    >>> s = make_random_stream(17, 299317, 13, 2**20)    >>> stream_to_list(s, 10)    [17, 894098, 115783, 383424, 775373, 994174, 941859, 558412, 238793, 718506]    """    "*** YOUR CODE HERE ***"

1. <span class="hljs-keyword">from</span> operator <span class="hljs-keyword">import</span> add, mul, mod
   
2. 
   
3. <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">make_random_stream</span><span class="hljs-params">(seed, a, c, n)</span>:</span>
   
4.     <span class="hljs-string">"""The infinite stream of pseudo-random numbers generated by the
   
5.     recurrence r[0] = SEED, r[i+1] = (r[i] * A + C) % N.  Your solution
   
6.     must not use any lambdas or def's that we have not supplied in the
   
7.     skeleton.
   
8.     >>> s = make_random_stream(25, 29, 5, 32)
   
9.     >>> stream_to_list(s, 10)
   
10.     [25, 26, 23, 0, 5, 22, 3, 28, 17, 18]
    
11.     >>> s = make_random_stream(17, 299317, 13, 2**20)
    
12.     >>> stream_to_list(s, 10)
    
13.     [17, 894098, 115783, 383424, 775373, 994174, 941859, 558412, 238793, 718506]
    
14.     """</span>
    
15. 
    
16.     <span class="hljs-string">"*** YOUR CODE HERE ***"<p style="line-height: 30px; text-indent: 2em;"></p></span>

复制代码

这个递归关系挺简单的吧， 最好还是自己试着写写看。61A跟一遍下来会很有收获的