Code Destine

Problem Statement

There is a special keyboard with all keys in a single row.

You have given a string keyboard of length 26 indicating the layout of the keyboard (indexed from 0 to 25), initially your finger is at index 0. To type a character, you have to move your finger to the index of the desired character. The time taken to move your finger from index i to index j is |i – j|.

You want to type a string word. Write a program to calculate how much time it takes to type it with one finger.

Example 

Input :- Keyboard = "abcdefghijklmnopqrstuvwxyz", Word = "cba"
Output :- 4

Input :- Keyboard = "pqrstuvwxyzabcdefghijklmno", Word = "hello"
Output :- 31

Solution

This problem can be solved in following steps :-

1. Create the character array from both the input String keyboard and word.
2. Create an integer array (count array) of size 26 (Total number of characters in the English language), This array will be used to store the index of each character in the keyboard string.
3. Traverse the character array keyboard from start (index 0) to end (n-1, where n is the length of an array) and convert each character into an index of count array by subtracting the character from ‘a’ and converting it into ASCII code. Assign the keyboard index to the calculated index.
4. Traverse the character array word from start (index 0) to end (n-1, where n is the length of an array) and for each character calculate the difference between new position of the character and the position of the finger. Update the position of the finger as new position of the character.
5. Add all the difference calculated in the last step and return it as an result.

Program

public class Main {

	public static void main(String[] args) {		
		Main main = new Main();
		int result = main.calculateTime("pqrstuvwxyzabcdefghijklmno", "hello");
		System.out.println(result);
	}
	
	/* Solution */
	public int calculateTime(String keyboard, String word) {
        
		char[] chars = keyboard.toCharArray();		
		int[] countArray = new int[26];
		for(int i=0; i<countArray.length; i++) {
			countArray[chars[i] - 'a'] = i;
		}
		
		int result = 0, position = 0;		
		char[] charsWord = word.toCharArray();
		for(int i=0; i<charsWord.length; i++) {
			result = result +  Math.abs(countArray[charsWord[i] - 'a'] - position);
			position = countArray[charsWord[i] - 'a'];
		}
		return result;
    }
}

Result

31

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