Length of Last Word - LeetCode : Swift

Length of Last Word - LeetCode

Given a string s consisting of words and spaces, return the length of the last word in the string. A word is a maximal substring consisting of non-space characters only.

Example 1:

Input: s = “Hello World”
Output: 5
Explanation: The last word is “World” with length 5.

Example 2:

Input: s = " fly me to the moon "
Output: 4
Explanation: The last word is “moon” with length 4.

Example 3:

Input: s = “luffy is still joyboy”
Output: 6
Explanation: The last word is “joyboy” with length 6.

Constraints:

• 1 <= s.length <= 104
• s consists of only English letters and spaces ' '.
• There will be at least one word in s.

Solution

class Solution {
    func lengthOfLastWord(_ s: String) -> Int {
        var str = (s as NSString).trimmingCharacters(in: [" "])
        if let spaceIndex = str.lastIndex(of: " ") {
           return  str.count - 1 - str.distance(from: str.startIndex, to: spaceIndex)
        }
        return str.count
    }
}