What is the key strategy for solving the 'Number of Segments in a String' problem?

The key strategy is to process the string efficiently by counting contiguous sequences of non-space characters, ensuring that spaces don't contribute to the segment count.

How do I handle multiple spaces in the 'Number of Segments in a String' problem?

When splitting the string by spaces, ignore any resulting empty segments caused by multiple spaces between words.

What is the time complexity of solving the 'Number of Segments in a String' problem?

The time complexity is generally O(n), where n is the length of the string. Both the iterative approach and splitting by spaces operate in linear time.

Can the 'Number of Segments in a String' problem be solved using regular expressions?

Yes, regular expressions can be used to identify and count sequences of non-space characters efficiently.

What should I avoid when solving the 'Number of Segments in a String' problem?

Avoid unnecessary operations like scanning the string repeatedly. It's best to handle the string in one pass or use efficient methods like splitting and regular expressions.

#434

Easy

auto_awesomeString-driven solution strategy

LeetCode 题解工作台

字符串中的单词数

统计字符串中的单词个数，这里的单词指的是连续的不是空格的字符。请注意，你可以假定字符串里不包括任何不可打印的字符。示例: 输入: "Hello, my name is John" 输出: 5 解释: 这里的单词是指连续的不是空格的字符，所以 "Hello," 算作 1 个单词。

字符串

题目描述

统计字符串中的单词个数，这里的单词指的是连续的不是空格的字符。

请注意，你可以假定字符串里不包括任何不可打印的字符。

示例:

输入: "Hello, my name is John"
输出: 5
解释: 这里的单词是指连续的不是空格的字符，所以 "Hello," 算作 1 个单词。

lightbulb

解题思路

方法一：字符串分割

我们将字符串 $\textit{s}$ 按照空格进行分割，然后统计不为空的单词个数。

时间复杂度 $O(n)$ ，空间复杂度 $O(n)$ 。其中 $n$ 为字符串 $\textit{s}$ 的长度。

1

2

3

4

class Solution:
    def countSegments(self, s: str) -> int:
        return len(s.split())

speed

复杂度分析

指标	值
时间	Depends on the final approach
空间	Depends on the final approach

psychology

面试官常问的追问

外企场景

question_mark
Candidate demonstrates a clear understanding of how to handle spaces and non-space characters in the string.
question_mark
Candidate uses an efficient strategy to avoid unnecessary operations, such as splitting on all spaces.
question_mark
Candidate can explain how to optimize for edge cases, such as leading, trailing, or multiple spaces.

warning

常见陷阱

外企场景

error
Not handling leading or trailing spaces correctly, which might lead to inaccurate segment counts.
error
Forgetting to exclude empty segments when splitting the string, especially when multiple spaces are used.
error
Using inefficient methods like repeatedly scanning the string for spaces instead of processing the string in a single pass.

swap_horiz

进阶变体

外企场景

arrow_right_alt
The input string contains leading or trailing spaces.
arrow_right_alt
The input string contains multiple consecutive spaces.
arrow_right_alt
The input string is empty or consists only of spaces.

help

常见问题

外企场景

继续练习

#433 最小基因变化 #438 找到字符串中所有字母异位词 #443 压缩字符串