LeetCode-in-Java
3794. Reverse String Prefix
Easy
You are given a string s and an integer k.
Reverse the first k characters of s and return the resulting string.
Example 1:
Input: s = “abcd”, k = 2
Output: “bacd”
Explanation:
The first k = 2 characters "ab" are reversed to "ba". The final resulting string is "bacd".
Example 2:
Input: s = “xyz”, k = 3
Output: “zyx”
Explanation:
The first k = 3 characters "xyz" are reversed to "zyx". The final resulting string is "zyx".
Example 3:
Input: s = “hey”, k = 1
Output: “hey”
Explanation:
The first k = 1 character "h" remains unchanged on reversal. The final resulting string is "hey".
Constraints:
1 <= s.length <= 100sconsists of lowercase English letters.1 <= k <= s.length
Solution
public class Solution {
public String reversePrefix(String s, int k) {
char[] arr = s.toCharArray();
for (int i = 0; i < k / 2; i++) {
char temp = arr[i];
arr[i] = arr[k - 1 - i];
arr[k - 1 - i] = temp;
}
return new String(arr);
}
}