Formatted question description: https://leetcode.ca/all/917.html
917. Reverse Only Letters (Easy)
Given a string S
, return the "reversed" string where all characters that are not a letter stay in the same place, and all letters reverse their positions.
Example 1:
Input: "ab-cd" Output: "dc-ba"
Example 2:
Input: "a-bC-dEf-ghIj" Output: "j-Ih-gfE-dCba"
Example 3:
Input: "Test1ng-Leet=code-Q!" Output: "Qedo1ct-eeLg=ntse-T!"
Note:
S.length <= 100
33 <= S[i].ASCIIcode <= 122
S
doesn't contain\
or"
Companies:
Microsoft
Related Topics:
String
Solution 1.
// OJ: https://leetcode.com/problems/reverse-only-letters/
// Time: O(N)
// Space: O(1)
class Solution {
public:
string reverseOnlyLetters(string S) {
int i = 0, j = S.size() - 1;
while (i < j) {
while (i < j && !isalpha(S[i])) ++i;
while (i < j && !isalpha(S[j])) --j;
if (i < j) swap(S[i++], S[j--]);
}
return S;
}
};
Java
-
class Solution { public String reverseOnlyLetters(String S) { char[] array = S.toCharArray(); int low = 0, high = array.length - 1; while (low < high) { char c1 = array[low], c2 = array[high]; if (Character.isLetter(c1) && Character.isLetter(c2)) { array[low] = c2; array[high] = c1; low++; high--; } else { if (!Character.isLetter(c1)) low++; if (!Character.isLetter(c2)) high--; } } return new String(array); } }
-
// OJ: https://leetcode.com/problems/reverse-only-letters/ // Time: O(N) // Space: O(1) class Solution { public: string reverseOnlyLetters(string S) { int i = 0, j = S.size() - 1; while (i < j) { while (i < j && !isalpha(S[i])) ++i; while (i < j && !isalpha(S[j])) --j; if (i < j) swap(S[i++], S[j--]); } return S; } };
-
class Solution(object): def reverseOnlyLetters(self, S): """ :type S: str :rtype: str """ letters = [] N = len(S) for i, s in enumerate(S): if s.isalpha(): letters.append(s) res = "" for i, s in enumerate(S): if s.isalpha(): res += letters.pop() else: res += s return res