LeetCode Link: 345. Reverse Vowels of a String
Language: C#
Problem Statement
Given a string s, reverse only all the vowels in the string and return it.
The vowels are ‘a’, ‘e’, ‘i’, ‘o’, and ‘u’, and they can appear in both lower and upper cases, more than once.
Examples
Example 1:
Input: s = “hello” Output: “holle”
Example 2:
Input: s = “leetcode” Output: “leotcede”
Constraints
- 1 <= s.length <= 3 * 105
- s consist of printable ASCII characters.
Solution
public class Solution
{
public string ReverseVowels(string s)
{
if (s.Length == 1)
{
return s;
}
char[] vow = ['a','e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'];
var tmp = new int[s.Length];
var c = 0;
for (int i=0; i < s.Length; i++)
{
if (vow.Contains(s[i]))
{
tmp[c] = i;
c++;
}
}
if (c == 0)
{
return s;
}
var last = c-1;
c = 0;
var o = new StringBuilder();
for (int i=0; i < s.Length; i++)
{
if (i == tmp[c])
{
o.Append(s[tmp[last]]);
last--;
c++;
continue;
}
o.Append(s[i]);
}
return o.ToString();
}
}
Complexity
Time Complexity: O(N)
Space Complexity: O(N)