58. Length of Last Word

🟢   🔖  字符串  🔗 LeetCode

题目

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 <= 10^4
• s consists of only English letters and spaces ' '.
• There will be at least one word in s.

题目大意

给你一个字符串  s，由若干单词组成，单词前后用一些空格字符隔开。返回字符串中最后一个单词的长度。单词  是指仅由字母组成、不包含任何空格字符的最大子字符串。

解题思路

• 先 trim 过滤掉尾部的空格，再用最后一个字符的下标，减去最后一个空格下标，即为单词的长度。

代码

/**
 * @param {string} s
 * @return {number}
 */
var lengthOfLastWord = function (s) {
	s = s.trim();
	return s.length - 1 - s.lastIndexOf(' ');
};