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Python | Check whether two lists are circularly identical
  • Last Updated : 11 May, 2020
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Given two lists, check if they are circularly identical or not.

Check whether two lists are circularly identical

Examples:

Input : list1 = [10, 10, 0, 0, 10]
        list2 = [10, 10, 10, 0, 0]
Output : Yes
Explanation: yes they are circularly identical as when we write the list1
             last index to second last index, then we find it is circularly
             same with list1 
Input : list1 = [10, 10, 10, 0, 0]
        list2 = [1, 10, 10, 0, 0]
Output :No

Method 1 : Using List Traversal



Using traversal, we have to double the given list. Check for any x(0<=n) to any x+n and compare with list2 to see if the list1 and list2 are same, if both are same then the list2 is circularly identical. Using two loops, check this property. The first loop will run from 0 to len(list1) and then check if the index (x to x+n) is same as list2, if yes then return true, else return false.

Below is the Python implementation of the above approach:




# python program to check if two 
# lists are circularly identical
# using traversal
  
# function to check circularly identical or not
def circularly_identical(list1, list2):
      
    # doubling list
    list3 = list1 * 2
      
    # traversal in twice of list1
    for x in range(0, len(list1)):
        z = 0 
          
        # check if list2 == list1 curcularly 
        for y in range(x, x + len(list1)):
            if list2[z]== list3[y]:
                z+= 1
            else:
                break
              
        # if all n elements are same circularly 
        if z == len(list1):
            return True 
      
    return False
          
  
  
# driver code
list1 = [10, 10, 0, 0, 10]
list2 = [10, 10, 10, 0, 0]
list3 = [1, 10, 10, 0, 0]
  
  
# check for list 1 and list 2 
if(circularly_identical(list1, list2)):
    print("Yes")
else:
    print("No")
  
# check for list 2 and list 3 
if(circularly_identical(list2, list3)):
    print ("Yes"
else:
    print ("No"
Output:
Yes
No

Method 2 : Using List Slicing




# python program to check if two 
# lists are circularly identical
# using traversal
   
# function to check circularly identical or not
def circularly_identical(list1, list2):
   
  # doubling list
  list1.extend(list1)
   
  # traversal in twice of list1
  for i in range(len(list1)):
   
    # check if sliced list1 is equal to list2
    if list2 == list1[i: i + len(list2)]:
   
      return True
  return False
  
  
# driver code
list1 = [10, 10, 0, 0, 10]
list2 = [10, 10, 10, 0, 0]
list3 = [1, 10, 10, 0, 0]
  
  
# check for list 1 and list 2 
if(circularly_identical(list1, list2)):
    print("Yes")
else:
    print("No")
  
# check for list 2 and list 3 
if(circularly_identical(list2, list3)):
    print ("Yes"
else:
    print ("No"
Output:
Yes
No

Method 3 : Using map() function

Using Python’s inbuilt function map() we can do this in one single step, where we have to map list2 in a string and then see if it exists in the mapping of twice of list1 (2*list1) in another string.

Below is the Python implementation of the above approach:




# python program to check if two 
# lists are circularly identical
# using map function 
  
# function to check circularly identical or not
def circularly_identical(list1, list2):
     
    return(' '.join(map(str, list2)) in ' '.join(map(str, list1 * 2)))
      
  
# driver code
list1 = [10, 10, 0, 0, 10]
list2 = [10, 10, 10, 0, 0]
list3 = [1, 10, 10, 0, 0]
  
  
# check for list 1 and list 2 
if (circularly_identical(list1, list2)):
    print("Yes")
else:
    print("No")
  
# check for list 2 and list 3 
if(circularly_identical(list2, list3)):
    print ("Yes"
else:
    print ("No"
Output:
Yes
No

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