Reverse Only Letters Problem & Solution
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.
See the reverse only letters problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
class Solution {
public:
string reverseOnlyLetters(string s) {
int low = 0;
int high = s.size() - 1;
while (low < high) {
char llow = tolower(s[low]);
if (llow < 'a' || llow > 'z') {
++low;
continue;
}
char lhigh = tolower(s[high]);
if (lhigh < 'a' || lhigh > 'z') {
--high;
continue;
}
swap(s[low], s[high]);
++low;
--high;
}
return s;
}
};