Reverse Words in a String III

Problem

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

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.

Solution

The problem Reverse Words in a String III can be solved by finding words separated by whitespaces and reversing each of them.

Implementation

class Solution
{
  public:
    string reverseWords(string s)
    {
        s += ' ';

        int left = 0;
        for (int right = 0; right < s.length(); right++)
            if (s[right] == ' ')
            {
                reverse(s.begin() + left, s.begin() + right);
                left = right + 1;
            }

        s.pop_back();
        return s;
    }
};