Today I have done leetcode's September LeetCoding Challenge with cpp.

September LeetCoding Challenge 22

Description

Reverse Words in a String III

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 * 10^4
• 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

class Solution {
public:
  string reverseWords(string s) {
    bool isSpace = true;
    int start = -1;
    for (int i = 0; i < s.length(); ++i) {
      if(isSpace && s[i] != ' ') {
        start = i;
      } else if(!isSpace && s[i] == ' ') {
        reverse(s.begin() + start, s.begin() + i);
      }
      isSpace = s[i] == ' ';
    }
    if(!isSpace) reverse(s.begin() + start, s.end());
    return s;
  }
};

// Accepted
// 29/29 cases passed (48 ms)
// Your runtime beats 16.64 % of cpp submissions
// Your memory usage beats 45.42 % of cpp submissions (9.7 MB)