There will be two rounds of problem-solving. I will ask you to solve one problem and code it up in each round of the interview. Finally, in the HR round, you will be asked very generic HR round questions, and a little more about system design and OOPs concepts.

First round: You are given a dictionary of 'm' words and a starting string. Your task is to transform the starting string into an ending string by changing one character at a time. Each intermediate word formed during the transformation must exist in the dictionary. You need to find the least number of transformations required to change the start string into the end string. Finally, print all such possible transformation sequences, with each step of the transformation presented as a complete sentence.