58. Length of Last Word

🟩 Easy

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: Output: 5 Explanation: Example 2:

Input: Output: 4 Explanation: Example 3:

Input: Output: 6 Explanation:

Constraints:

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 <= 10^4

• s consists of only English letters and spaces ' '.

• There will be at least one word in s.

Solution

My Solution

func lengthOfLastWord(s string) int {
    cnt := 0
    existEmpty := false
    for _, v := range s {
        if v == ' ' {
            existEmpty = true
        } else {
            if existEmpty {
                cnt = 0
                existEmpty = false
            }
            cnt++
        }
    }

    return cnt
}

Optimal solution

func lengthOfLastWord(s string) int {
    length := 0
    i := len(s) - 1

    // Ignore trailing spaces
    for i >= 0 && s[i] == ' ' {
        i--
    }

    // Count the length of the last word
    for i >= 0 && s[i] != ' ' {
        length++
        i--
    }

    return length
}

result

Leetcode: link