PPractick

The problem

A kids' puzzle app shows sentences with every word spelled backwards while the words stay in their original order and positions, like "Mr Ding" → "rM gniD", and players guess the sentence. The transformation reverses the characters of each word in place, leaving the spaces exactly where they are. It's a two-pointer string exercise: find each word's boundaries and reverse that range. (Reversing the order of the words, rather than their letters, is S.No 135.)

Example: "Let's take LeetCode contest" → "s'teL ekat edoCteeL tsetnoc".

Function signature

string reverseEachWord(string s);  // reverses each word's characters; spaces stay in place

Test cases

Input s	Output	Explanation
"Let's take LeetCode contest"	"s'teL ekat edoCteeL tsetnoc"	Each word reversed, order kept
"Mr Ding"	"rM gniD"
"a"	"a"
"ab cd"	"ba dc"
" hi "	" ih "	Spaces are preserved exactly

(Confirm: words are separated by spaces; the word order and all spaces stay the same; punctuation belongs to the word.)

How interviewers phrase it

• "Reverse the characters of each word while keeping the word order" (LeetCode 557).
• Often paired with "reverse the order of the words" (LeetCode 151, S.No 135) to see whether you distinguish the two.

Clarifying questions to ask

1. Reverse the letters of each word, or the order of the words?
2. Should spaces be preserved exactly, including repeated spaces?
3. Is in-place modification allowed?

Follow-ups to expect

1. "How do you find the words?"
2. "How does this relate to reversing the word order?"
3. "What's the extra space?"
4. "Complexity?"

Related questions

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• Check if String is Palindrome or Not Easy
• Sort an array of 0's 1's and 2's Medium
• Rearrange array elements by sign Medium
• Next Permutation Medium
• 3 Sum Medium

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