logseq_notes/pages/OJ notes/pages/Leetcode Reverse-Words-In-a-String.md

Leetcode Reverse-Words-In-a-String

2022-07-12 09:10

Algorithms:

#algorithm #two_pointers

Data structures:

#DS #string

Difficulty:

#coding_problems #difficulty_easy

Additional tags:

#leetcode

Revisions:

N/A

Related topics:

Links:

• Link to problem

  ---

Problem

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

Examples

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.

Thoughts

[!summary] This is a #two_pointers

very easy and intuitive.

Solution

class Solution {
void reverse(string &s, int l, int r) {
  if (l >= r) {
    return;
  }
  swap(s[l++], s[r--]);
  reverse(s, l, r);
}

public:
string reverseWords(string s) {
  int slow = 0, fast;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == ' ') {
      fast = i - 1;
      reverse(s, slow, fast);
      slow = i + 1;
    }
  }
  reverse(s, slow, s.size() - 1);
  return s;
}
};