what is the time complexity of phone keypad solution implemented in the video.tell with some explanation
Time complexity keypad issue
@Rj.25 hey, think about how many outputs there are, and how long it takes to compute an output.
If you have n characters, each of which maps to k options, then the number of possible results is k^n. The complexity of your algorithm is therefore at least k^n, or Omega(k^n), because O(k^n) outputs are enumerated.
We still need to consider how long it takes to compute each input. Notice that you’re building a String of length n by adding one character at a time. Since Strings are immutable, every time you add a character, an entirely new String must be created. The work involved to produce a String of length n by appending characters is 1 + 2 + … + n = O(n^2).
We can just multiply the number of results by the work for each result, to arrive at the final complexity O(n^2 * k^n), or more specifically, Theta(n^2 * k^n).
Hope you get it 
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