Problem List

Valid Palindrome

May 30, 2025 • Go • string, two pointer • easy

Problem

Given a string s, return true if it is a palindrome, or false otherwise.

Approach

1. Clean up the string by converting to lower case then removing whitespace/checking the rune values.
2. Compare the left and right side moving inward with two pointers

Edge Cases

' ' -> true

Reflections

This was a horrendous approach. I need to study up on runes, ASCII, and strings mutation.

Performance

Runtime beats: 10%
Memory beats: 10%

Complexity

Time: O(n)
Space: O(n)

Go Solution

import "strings"

func isPalindrome(s string) bool {
  s = formatString(s)
  fmt.Print(s)
  left, right := 0, len(s) - 1
  for left <= right {
    leftLetter, rightLetter:= s[left], s[right]

        if leftLetter != rightLetter  {
      return false
    }

        left++
  right--
}

return true
}

func formatString(s string) string {
  s = strings.ToLower(s)
  s = strings.TrimSpace(s)

  res:= ""
  for _, letter := range s {

    if (letter >= 'a' && letter <= 'z') || (letter >= '0' && letter <= '9') {
      res += string(letter)
    }
  }

  return res
};

LeetCode Problem Link