20190108 use of recursive function to realize the use of basic recursive functions such as finding the greatest common divisor

1. Given a = [1,2,[3,4,[5,6,7,[8,9,[10,11]]]], print output is required: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Use the recursive function to traverse A. when the value of a is list, continue to call the recursive function, and take values one by one

def iter_list(l):
    for i in l:
        if isinstance(i,list):
            iter_list(i)
#The elements in the list passed in before are list Call the recursive function
        else:
            print(i,end =' ')
iter_list(a)

2. Make the result a list based on the first question

#Method 1
def iter_list(l,result=[]):
    #result Is the default parameter, which is used when no value is passed result=[],Use the value passed in when passing the value
    for i in l:
        if isinstance(i,list):
            iter_list2(i,result)
        else:
            result.append(i)
    return result
print(iter_list(a))
#Method 2
def iter_list2(l,result):
       for i in l:
        if isinstance(i,list):
            iter_list2(i,result)
        else:
            result.append(i)
    return result
result =[]
print(iter_list2(a,result))

3. Write a method recursively to output n,n-1....10, 9, 8... 1 to 0 end

#algorithm:Print each number, exit recursion when the number is less than 0
def output_num(n):
    print(n)
    if n>0:
        output_num(n-1)
    else:
        print('----')
output_num(5)

4. Using recursive function to write a method to find the maximum co constraint

#Algorithm: use the rolling phase division method for the maximum common divisor
Find (319377):
∵ 319 ÷ 377 = 0 (balance 319)
∴(319,377)=(377,319);
∵ 377 ÷ 319 = 1 (remaining 58)
∴(377,319)=(319,58);
∵ 319 ÷ 58 = 5 (remaining 29)
∴ (319,58)=(58,29);
∵ 58 ÷ 29 = 2 (remaining 0)
∴ (58,29)= 29;
∴ (319,377)=29

def find_max_common_divisor(a,b):
    if a<b:
        a,b = b,a
        print(a,b)
       #ensure a>b
    if a%b!=0:
        print('a%b Branch taken')
        temp = b
        b = a%b
        a = temp
        print(a,b)
        return find_max_common_divisor(a,b)
        #return There is a short-circuit effect. The following statements will not be executed
    else:
        return b
print(find_max_common_divisor(319,377))

Tags: Python less

Posted on Wed, 04 Dec 2019 13:08:24 -0500 by minifairy