LeetCode-in-Java

3823. Reverse Letters Then Special Characters in a String

Easy

You are given a string s consisting of lowercase English letters and special characters.

Your task is to perform these in order:

• Reverse the lowercase letters and place them back into the positions originally occupied by letters.
• Reverse the special characters and place them back into the positions originally occupied by special characters.

Return the resulting string after performing the reversals.

Example 1:

Input: s = “)ebc#da@f(“

Output: “(fad@cb#e)”

Explanation:

• The letters in the string are ['e', 'b', 'c', 'd', 'a', 'f']:
  • Reversing them gives ['f', 'a', 'd', 'c', 'b', 'e']
  • s becomes ")fad#cb@e("
• The special characters in the string are [')', '#', '@', '(']:
  • Reversing them gives ['(', '@', '#', ')']
  • s becomes "(fad@cb#e)"

Example 2:

Input: s = “z”

Output: “z”

Explanation:

The string contains only one letter, and reversing it does not change the string. There are no special characters.

Example 3:

Input: s = “!@#$%^&*()”

Output: “)(*&^%$#@!”

Explanation:

The string contains no letters. The string contains all special characters, so reversing the special characters reverses the whole string.

Constraints:

• 1 <= s.length <= 100
• s consists only of lowercase English letters and the special characters in "!@#$%^&*()".

Solution

public class Solution {
    public String reverseByType(String s) {
        char[] arr = s.toCharArray();
        int low = 0;
        int high = arr.length - 1;
        while (low < high) {
            if (arr[low] >= 'a' && arr[low] <= 'z' && arr[high] >= 'a' && arr[high] <= 'z') {
                char t = arr[low];
                arr[low] = arr[high];
                arr[high] = t;
                low++;
                high--;
            } else if (arr[low] < 'a' || arr[low] > 'z') {
                low++;
            } else {
                high--;
            }
        }
        int i = 0;
        int j = arr.length - 1;
        while (i < j) {
            if ((arr[i] < 'a' || arr[i] > 'z') && (arr[j] < 'a' || arr[j] > 'z')) {
                char t = arr[i];
                arr[i] = arr[j];
                arr[j] = t;
                i++;
                j--;
            } else if (arr[i] >= 'a' && arr[i] <= 'z') {
                i++;
            } else {
                j--;
            }
        }
        return new String(arr);
    }
}

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