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Grokking the Coding Interview Patterns in JavaScript

Word Ladder

Explore how to apply breadth-first search to solve the Word Ladder problem by finding the shortest path transforming one word into another. Understand problem constraints and build a clear approach to tackle similar coding interview challenges using BFS.

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Statement

Given two words, src and dest, and a list, words, return the number of words in the shortest transformation sequence from src to dest. If no such sequence can be formed, return 00.

A transformation sequence is a sequence of words ((src →\to word1word_1 →\to word2word_2 →\to word3word_3 ...... →\to wordjword_j )) that has the following properties:

  • wordj=word_j = dest
  • Every pair of consecutive words differs by a single character.
  • All the words in the sequence are present in the words. The src does not need to be present in words.

Constraints:

  • 1≤1 \leq src.length ≤10\leq 10

  • src.length == dest.length == words[i].length

  • src ≠\neq dest

  • 1≤1 \leq words.length ≤5000\leq 5000

  • No duplicates in the words

  • src, dest, and words[i] consist of lowercase English characters.

Examples

Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Word Ladder

1.

What’s the correct output for the following inputs?

src = “hit”

dest = “cog”

words = [“log”, “dot”, “lot”, “dog”, “hot”, “cog”]

A.

5

B.

6

C.

0

D.

7

1 / 3

Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.
1
2
3
4
5

Try it yourself

Implement your solution in main.js in the following coding playground. We have provided a useful code template in the other file that you may build on to solve this problem.

JavaScript
usercode > main.js
import Queue from "./queue.js";



function wordLadder(src, dest, words) {

    

    // Replace this placeholder return statement with your code

    return -1;

}



export { wordLadder };
Word Ladder