58. Length of Last Word

Length of Last Word

Problem Description

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.

Approach) Without Split

var lengthOfLastWord = function(s) {
     
    let index = s.length - 1;
    let output = 0;

    while (s[index] === ' ' && index >= 0) index -= 1;

    while (s[index] !== ' ' && index >= 0) {

        output += 1;
        index -= 1;

    }
    return output;
};

Approach) One Liner

/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLastWord = function(s) {
     return s.trim().split(' ').pop().length;

};

Approach) Inbuilt Function

/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLastWord = function(s) {
   return s
        .split(' ')
        .filter(char => char)
        .pop()
        .length;
};

Approach) Regex

/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLastWord = function(s) {
    let m = s.trim().match(/(\w)+$/)
    return m ? m[0].length : 0;
};

Conclusion

That’s all folks! In this post, we solved LeetCode problem 58. Length of Last Word

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Happy coding!