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Topic 1004: the story of cows (recursion)

2022-07-01 12:35:00 【51CTO】

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Question
Ideas
Code

Question

       
        Title Description 
       
        There is a cow , It gives birth to a heifer every year . Each heifer starts from the fourth year , A heifer is born at the beginning of each year . Please programmatically implement in Section n In the year , How many cows are there ？
       
        Input 
       
        The input data consists of multiple test cases , One line per test instance , Include an integer n(
       
       0
       
       <
       
       n
       
       <
       
       55)
       
       ,n The meaning of is described in the title .
       
       n
       
       =
       
       0
       
        Indicates the end of the input data , Don't deal with it .
       
        Output 
       
        For each test case , The output is in the second n The number of cows in the year .
       
        One line per output .
       
        The sample input 
       
       2
       
       4
       
       5
       
       0
       
        Sample output 
       
       2
       
       4
       
       6
      
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Ideas

The first n Number of cattle in = The first n-1 Number of cattle in + The first n-3 Number of years ago （ Calves can be born in four years ）

Code

       
       #  Recurrence 
       
       list 
       
       = []
       
       # Definition list 
       
       list.
       
       append(
       
       0)
       
       #  Go to list Add initial data 
       
       list.
       
       append(
       
       1)
       
       #  The number of cows in the first year is 1
       
       list.
       
       append(
       
       2)
       
       #  The number of cows in the first year is 2
       
       list.
       
       append(
       
       3)
       
       #  The number of cows in the first year is 3
       
       for 
       
       i 
       
       in 
       
       range(
       
       4,
       
       1000):  
       
       # Before pretreatment 1000 Number of cows in 
       
       list.
       
       append(
       
       list[
       
       i
       
       -
       
       1]
       
       +
       
       list[
       
       i
       
       -
       
       3])
       
       while 
       
       True:  
       
       n 
       
       = 
       
       int(
       
       input())
       
       # Convert to integer 
       
       if 
       
       n
       
       ==
       
       0:        
       
       #n ==0  Exit from time  
       
       break
       
       print(
       
       list[
       
       n])  
       
       # It has been pretreated , All direct output is OK 
      
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