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solution.go
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solution.go
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package valid_palindrome
import (
"regexp"
"strings"
)
func isPalindrome(s string) bool {
r := regexp.MustCompile(`(?i)[^0-9a-z]+`)
s = strings.ToLower(r.ReplaceAllString(s, ""))
left, right := 0, len(s)-1
for left < right {
if s[left] != s[right] {
return false
}
left++
right--
}
return true
}
func isPalindromeV2(s string) bool {
const letterCaseCodesDiff = uint8(rune('a') - rune('A'))
left, right := 0, len(s)-1
for left < right {
leftVal, rightVal := s[left], s[right]
// Convert uppercase to lower
if leftVal >= 'A' && leftVal <= 'Z' {
leftVal += letterCaseCodesDiff
}
if rightVal >= 'A' && rightVal <= 'Z' {
rightVal += letterCaseCodesDiff
}
// Check symbols
if leftVal < '0' || leftVal > 'z' || (leftVal > '9' && leftVal < 'a') {
left++
continue
}
if rightVal < '0' || rightVal > 'z' || (rightVal > '9' && rightVal < 'a') {
right--
continue
}
// Compare
if leftVal != rightVal {
return false
}
left++
right--
}
return true
}