1165. Single-Row Keyboard

Tags: ‘String’

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

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 function to calculate how much time it takes to type it with one finger.

Example 1:

Input: keyboard = "abcdefghijklmnopqrstuvwxyz", word = "cba"
Output: 4
Explanation: The index moves from 0 to 2 to write 'c' then to 1 to write 'b' then to 0 again to write 'a'.
Total time = 2 + 1 + 1 = 4.

Example 2:

Input: keyboard = "pqrstuvwxyzabcdefghijklmno", word = "leetcode"
Output: 73

Constraints:

keyboard.length == 26
keyboard contains each English lowercase letter exactly once in some order.
1 <= word.length <= 10^4
word[i] is an English lowercase letter.

Solution

For alphabatic characters, we can use array instead of Map to store data

//use array
public int calculateTime(String keyboard, String word) {
    int[] index = new int[26];
    for (int i = 0; i < keyboard.length(); i++) {
        index[keyboard.charAt(i) - 'a'] = i;
    }
    
    int pre = 0;
    int result = 0;
    for (int i = 0; i < word.length(); i++) {
        result += Math.abs(pre - index[word.charAt(i) - 'a']);
        pre = index[word.charAt(i) - 'a'];
        System.out.println(result);
    }
    return result;
}

//15% 100%
public int calculateTime(String keyboard, String word) {
    Map<Character, Integer> map = new HashMap<>();
    for (int i = 0; i < keyboard.length(); i++) {
        map.put(keyboard.charAt(i), i);
    }
    
    int result = 0;
    for (int i = 1; i < word.length(); i++) {
        result += Math.abs(map.get(word.charAt(i-1)) - map.get(word.charAt(i)));
    }
    return result + map.get(word.charAt(0));
}

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1165. Single-Row Keyboard