Given a list of word lists of size M * N. The task is to return all sentences possible taking one word from a list at a time via recursion.
Example 1:
Input:
L = {{"you", "we"},
{"have", "are"},
Output:
{{you have}
{you are}
{we have}
{we are}}
Explanation:
Consider every every word from the list and form
sentences with every other words, taking one word from a list .
Note: You need to maintain the order of the sentences.
Your Task:
You don't need to read input or print anything. Your task is to complete the function sentences() which takes a matrix of strings as input and returns a matrix of string containing all possible sentences.
Expected Time Complexity: O(M^{N})
Expected Auxiliary Space: O(M^{N})

Constraints:
1 <= M, N <= 6
'a' <= sentence[i][j] <= 'z'

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