LeetCode 58 - Length of Last Word

• Difficulty: Easy.
• Related Topics: String.
• Link: leetcode

Problem

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

Example:

Input: "Hello World"
Output: 5

Solution

/**
 * @param {string} s
 * @return {number}
 */

var lengthOfLastWord = function (s) {
  if (s.length === 1) return 1;

  const words = s.trim().split(" ");
  const lastWordIndex = words.length - 1;
  return words.length > 0 ? words[lastWordIndex].length : 0;
};

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).

First thought (2023.09.07)

var lengthOfLastWord = function (s) {
  if (s.length === 1) return 1;

  let count = 0;

  for (let i = s.length - 1; i >= 0; i--) {
    if (s[i] !== " ") {
      count++;
    }

    if (count && s[i] === " ") {
      return count;
    }
  }
  return count;
};