Letter Combinations of a Phone Number – LeetCode Solutions

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LeetCode has a Medium coding Problem in Its’ Algorithm Section “Letter Combinations of a Phone Number”. Today We are going to solve this problem in Python. LeetCode Link of the Problem is HERE

Question

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.

A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.

Letter Combinations of a Phone Number

Examples

Input: digits = “23”
Output: [“ad”,”ae”,”af”,”bd”,”be”,”bf”,”cd”,”ce”,”cf”]

Input: digits = “”
Output: []

Input: digits = “2”
Output: [“a”,”b”,”c”]


Constraints:

  • 0 <= digits.length <= 4
  • digits[i] is a digit in the range ['2', '9'].

Solution to Letter Combinations of a Phone Number

def create(self,digits, index,m,ans,temp):

if index == len(digits):

return temp

for i in m[digits[index]]:

temp += i

if len(temp) == len(digits):

ans.append(temp)

else:

self.create(digits,index+1,m,ans,temp)

temp = temp[:-1]

return ans

Success

Runtime: 23 ms, faster than 56.19% of Python online submissions.

Memory Usage: 13.3 MB, less than 98.21% of Python online submissions.

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