17. Letter Combinations of a Phone Number

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Difficulty: Medium 

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

 

Example 1:

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

Example 2:

Input: digits = ""
Output: []

Example 3:

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

Python Solution:

class Solution:
 def letterCombinations(self, digits: str) -> List[str]:
 d={2:'abc',3:'def',4:'ghi',5:'jkl',6:'mno',7:'pqrs',8:'tuv',9:'wxyz'}
 i=0
 l=[]
 try:
 for i in d[int(digits[0])]:
 try:
 for j in d[int(digits[1])]:
 try:
 for k in d[int(digits[2])]:
 try:
 for m in d[int(digits[3])]:
 l.append(i+j+k+m)
 except:
 l.append(i+j+k)
 except:
 l.append(i+j)
 except:
 l.append(i)
 return l
 except:
 return l

If you have any doubt in code, just ask me in gmail, I'll clear your doubt: varunkapoor.29085@gmail.com

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