RUST GYM Leetcode 1165 Single-Row Keyboard Rust Solution

1165. Single-Row Keyboard

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.

Rust Solution

struct Solution;

impl Solution {
    fn calculate_time(keyboard: String, word: String) -> i32 {
        let mut indexes: Vec<i32> = vec![0; 26];
        for (i, b) in keyboard.bytes().enumerate() {
            indexes[(b - b'a') as usize] = i as i32;
        }
        let mut prev = 0;
        let mut sum = 0;
        for b in word.bytes() {
            let index = indexes[(b - b'a') as usize];
            sum += (index - prev).abs();
            prev = index;
        }
        sum
    }
}

#[test]
fn test() {
    let keyboard = "abcdefghijklmnopqrstuvwxyz".to_string();
    let word = "cba".to_string();
    assert_eq!(Solution::calculate_time(keyboard, word), 4);
    let keyboard = "pqrstuvwxyzabcdefghijklmno".to_string();
    let word = "leetcode".to_string();
    assert_eq!(Solution::calculate_time(keyboard, word), 73);
}

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