Is Reverse Words in a String III easy or hard?

Reverse Words in a String III is classified as an Easy problem on LeetCode with a high acceptance rate. It mainly tests basic string manipulation and familiarity with the two-pointer pattern.

How to solve Reverse Words in a String III in O(n)?

Traverse the string and detect word boundaries using spaces. For each word, apply a two-pointer reversal between its start and end indices. Because each character is processed only once, the algorithm completes in O(n) time.

Reverse Words in a String III Python or Java solution

In Python, a common solution uses split(), reverse slicing for each word, and join() to rebuild the sentence. In Java, you can convert the string to a char array and reverse each word using two pointers before constructing the final string.

What is the best approach for Reverse Words in a String III?

The two pointers inline reversal approach is considered the best solution. It scans the string once, identifies word boundaries, and reverses characters in place. This achieves O(n) time complexity with O(1) extra space, which is optimal for this problem.

What data structure is used in Reverse Words in a String III?

The problem primarily uses strings and sometimes a character array for in-place modification. The algorithm relies on the two-pointer technique to swap characters within each word efficiently.

What is the time complexity of Reverse Words in a String III?

The optimal time complexity is O(n), where n is the length of the input string. Each character is visited at most a constant number of times during scanning and reversal. Both the split-based and two-pointer solutions run in linear time.

Is Reverse Words in a String III asked at Google, Amazon, or Meta?

String manipulation problems like this frequently appear in coding interviews at companies such as Amazon, Google, and Meta. While this exact question may vary, the underlying patterns—two pointers and in-place string reversal—are common interview topics.

Description Solution Video 6:47

557. Reverse Words in a String III

Easy84.0% acceptance7 companies

Given a string s, reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: s = "Let's take LeetCode contest"
Output: "s'teL ekat edoCteeL tsetnoc"

Example 2:

Input: s = "Mr Ding"
Output: "rM gniD"

Constraints:

1 <= s.length <= 5 * 10⁴
s contains printable ASCII characters.
s does not contain any leading or trailing spaces.
There is at least one word in s.
All the words in s are separated by a single space.

Asked at 7 companies

Zappos Amazon Zoho Meta

Google Microsoft Bloomberg

Topics

String Two Pointers

6:47

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557. Reverse Words in a String III

Asked at 7 companies

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