Word Ladder I

Given two words (start and end), and a dictionary, find the length of shortest transformation sequence from start to end, such that:

  • You must change exactly one character in every transformation
  • Each intermediate word must exist in the dictionary

Example :


start = "hit"
end = "cog"
dict = ["hot","dot","dog","lot","log"]

As one shortest transformation is "hit" -> "hot" -> "dot" -> "dog" -> "cog",
return its length 5.

Note that we account for the length of the transformation path instead of the number of transformation itself.


  • Return 0 if there is no such transformation sequence.
  • All words have the same length.
  • All words contain only lowercase alphabetic characters.
NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a doubt? Checkout Sample Codes for more details.
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