Valid palindrome.
Given an input string. We have to write a code to check if it is a palindrome, considering only alphanumeric characters and ignoring cases.
Note: For this problem, consider the empty string as a valid palindrome.
For Example –
Example 1:
Input: “A man, a plan, a canal: Panama”
Output: true
Explanation: After removing non-alphanumeric characters, the string is amanaplanacanalpanama. So, it’s a palindrome
Example 2:
Input: “race a car”
Output: false
How to reverse words in a String?
In this problem, we have given an input string, we have to write a code to reverse the string word by word.
Example 1:
Input : “the carpet is green”
Output: “green is carpet the”
Example 2:
Input : ” Java Ebook “
Output: “Ebook Java”
Explanation: The reversed string should not contain leading or trailing spaces.
Example 3:
Input : “a good example”
Output: “example good a”
Explanation: We have reduce multiple spaces between two words to a single space in the reversed string.
Note:
Let’s discuss an interesting problem Backspace String Compare.
Given two strings S and T containing backspaces. We have to write a code to check if they are equal. In string, # means a backspace character.
Example 1:
Input: S = “ab#c”, T = “ad#c”
Output: true
Explanation: Both S and T become “ac”.
Example 2:
Input: S = “ab##”, T = “c#d#”
Output: true
Explanation: Both S and T become “”.
Example 3:
Input: S = “a##c”, T = “#a#c”
Output: true
Explanation: Both S and T become “c”.
Example 4:
Input: S = “a#c”, T = “b”
Output: false
Explanation: S becomes “c” while T becomes “b”.