Convert a Mobile Numeric Keypad sequence to equivalent sentence.
- coded using JavaScript (use node.js to run)
- Given a string sequence of size N, consisting of digits [0 – 9] and character ‘.’
- the task is to print the string that can be obtained by pressing the mobile keypad in the given sequence.
- The keyboard layout is:
| 1 |
2 (A,B,C) |
3 (D,E,F) |
| 4 (G,H,I) |
5 (J,K,L) |
6 (M,N,O) |
| 7 (P,Q,R,S) |
8 (T,U,V) |
9 (W,X,Y,Z) |
Note: ‘.’ represents a break while typing.
Approach: The given problem can be solved by storing the mobile keypad mappings in an array and then traverse the string 'sequence' and convert it into its equivalent string.
- Initialize an empty string, say ans to store the required result.
- Store the string associated to each key in the mobile keypad in an array nums[] such that nums[i] represent the set of characters on pressing the digit i.
- Traverse the given string S using the variable i and perform the following steps:
-
- If S[i] is equal to ‘.’, then increment i by 1, and continue to the next iteration.
- Otherwise, initialize a variable count as 0 to store the count of the same characters.
- Iterate until S[i] is equal to S[i + 1] and in each iteration check the following conditions:
- If count is equal to 3 and S[i] is 2, 3, 4, 5, 6, or 8, then break out of the loop because keys: 2, 3, 4, 5, 6, and 8 contain the same number of characters, i.e., 4.
- If count is equal to 4 and S[i] is 7 or 9, then break out of the loop because keys: 7 and 9 contain the same number of characters, i.e., 5.
- Increment the value of count and i by 1.
- If S[i] is either 7 or 9, then add the character nums[str[i]][count%5] to the string ans.
- Otherwise, add the character nums[str[i]][count%4] to the string ans.
- Increment the value of i by 1.
- After completing the above steps, return the ans string from the function and print in the main function.