# Python – K list Nested Dictionary Mesh

Given 2 lists, create nested mesh with constant List.

Input : test_list1 = [4, 6], test_list2 = [2, 7], K = [] Output : {4: {2: [], 7: []}, 6: {2: [], 7: []}} Explanation : Nested dictionary initialized with []. Input : test_list1 = [4], test_list2 = [2], K = [1] Output : {4: {2: [1]}} Explanation : Nested dictionary initialized with [1].

Method : Using dictionary comprehension

In this, we use nested dictionary comprehension, inner one for list 2 elements to each element of list 1 as key and outer to assign keys from list 1.

## Python3

 `# Python3 code to demonstrate working of ``# K list Nested Dictionary Mesh``# Using * operator` `# initializing lists``test_list1 ``=` `[``4``, ``6``, ``8``, ``7``]``test_list2 ``=` `[``2``, ``7``, ``9``, ``4``]` `# printing original lists``print``(``"The original list 1 : "` `+` `str``(test_list1))``print``(``"The original list 2 : "` `+` `str``(test_list2))` `# initializing K ``K ``=` `[``None``]` `# initializing K list mesh``res ``=` `{idx: {sub2: K ``for` `sub2 ``in` `test_list2} ``for` `idx ``in` `test_list1}` `# printing result ``print``(``"Created Mesh : "` `+` `str``(res))`

Output
```The original list 1 : [4, 6, 8, 7]
The original list 2 : [2, 7, 9, 4]
Created Mesh : {4: {2: [None], 7: [None], 9: [None], 4: [None]}, 6: {2: [None], 7: [None], 9: [None], 4: [None]}, 8: {2: [None], 7: [None], 9: [None], 4: [None]}, 7: {2: [None], 7: [None], 9: [None], 4: [None]}}```

Time complexity: O(n*n), where n is the length of the dictionary.
Auxiliary Space: O(n), extra space of size n is required

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