Reverse Words in a String III

Description

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 = “God Ding” Output: “doG 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.

Code

Time Complexity: $O(n)$, Space Complexity: $O(1)$

相比於 Reverse Words in a String 而言，因為 preserve the whitespace，簡單許多。

class Solution {
public:
    string reverseWords(string s) {
        int i = 0;
        for(int j = i; j < s.size(); j++) {
            if(s[j] == ' ') {
                reverse(s.begin() + i, s.begin() + j);
                i = j + 1;
            }
        }
        reverse(s.begin() + i, s.end());
        return s;
    }
};

Source

• Reverse Words in a String III - LeetCode