Reverse Only Letters Problem
Description
LeetCode Problem 917.
Given a string s, reverse the string according to the following rules:
- All the characters that are not English letters remain in the same position.
- All the English letters (lowercase or uppercase) should be reversed.
Return s after reversing it.
Example 1:
1
2
Input: s = "ab-cd"
Output: "dc-ba"
Example 2:
1
2
Input: s = "a-bC-dEf-ghIj"
Output: "j-Ih-gfE-dCba"
Example 3:
1
2
Input: s = "Test1ng-Leet=code-Q!"
Output: "Qedo1ct-eeLg=ntse-T!"
Constraints:
- 1 <= s.length <= 100
- s consists of characters with ASCII values in the range [33, 122].
- s does not contain ‘"’ or ‘\’.
Sample C++ Code
1
2
3
4
5
6
7
8
9
10
11
12
class Solution {
public:
string reverseOnlyLetters(string s) {
int l = 0, r = s.size() - 1;
while (l < r) {
while (l < r && !isalpha(s[l])) ++l;
while (l < r && !isalpha(s[r])) --r;
swap(s[l++], s[r--]);
}
return s;
}
};