SPtest

Question 1

Given a word, return the total number of key presses required to spell the word using the keypad.

Question 2

Given a word, return the number that the word could represent.

Question 3

Given a number, return all possible letter combinations that the number could represent.

Question 4

Given a number, return all possible word combinations (from Dictionary- pls see attached file) that the number could represent.

How To Run

1. From command line, enter

javac Solution.java
java Solution

2. When prompted for question number, enter an integer from 0 to 4.
   • 0 to exit the program
   • 1 - 4 for questions 1 to 4
3. After entering question number
   • Questions 1 & 2 - enter a word
   • Questions 3 & 4 - enter a number

Implementation

1. Parts 1 & 2 are implemented by first building a lookup table at the start of the program. The use of the lookup table makes it fast to get the corresponding key/number of presses for each character in the input string. Inputs are case-insensitive.
2. In parts 3 & 4, HashMap is used to store the characters corresponding to each key in the keypad.
3. Part 4 is implemented using a trie data structure to store the dictionary. This is done at the start of the program. Trie is used as it is suitable for dictionary representation and word lookup.