剑指 Offer II 018. 有效的回文

class Solution:
    def isPalindrome(self, s: str) -> bool:
        i, j = 0, len(s) - 1
        while i < j:
            while i < j and not s[i].isalnum():
                i += 1
            while i < j and not s[j].isalnum():
                j -= 1
            if s[i].lower() != s[j].lower():
                return False
            i, j = i + 1, j - 1
        return True

class Solution {
    public boolean isPalindrome(String s) {
        int i = 0, j = s.length() - 1;
        while (i < j) {
            while (i < j && !Character.isLetterOrDigit(s.charAt(i))) {
                ++i;
            }
            while (i < j && !Character.isLetterOrDigit(s.charAt(j))) {
                --j;
            }
            if (Character.toLowerCase(s.charAt(i)) != Character.toLowerCase(s.charAt(j))) {
                return false;
            }
            ++i;
            --j;
        }
        return true;
    }
}

class Solution {
public:
    bool isPalindrome(string s) {
        int i = 0, j = s.size() - 1;
        while (i < j) {
            while (i < j && !isalnum(s[i])) {
                ++i;
            }
            while (i < j && !isalnum(s[j])) {
                --j;
            }
            if (tolower(s[i]) != tolower(s[j])) {
                return false;
            }
            ++i;
            --j;
        }
        return true;
    }
};

func isPalindrome(s string) bool {
	i, j := 0, len(s)-1
	for i < j {
		for i < j && !isalnum(s[i]) {
			i++
		}
		for i < j && !isalnum(s[j]) {
			j--
		}
		if tolower(s[i]) != tolower(s[j]) {
			return false
		}
		i, j = i+1, j-1
	}
	return true
}

func tolower(b byte) byte {
	if b >= 'A' && b <= 'Z' {
		return b - 'A' + 'a'
	}
	return b
}

func isalnum(b byte) bool {
	return b >= '0' && b <= '9' ||
		b >= 'a' && b <= 'z' ||
		b >= 'A' && b <= 'Z'
}

function isPalindrome(s: string): boolean {
    const str = s.replace(/[^a-zA-Z0-9]/g, '');
    let l = 0;
    let r = str.length - 1;
    while (l < r) {
        if (str[l].toLocaleLowerCase() !== str[r].toLocaleLowerCase()) {
            return false;
        }
        l++;
        r--;
    }
    return true;
}

impl Solution {
    pub fn is_palindrome(s: String) -> bool {
        let ss: Vec<char> = s.chars().collect();
        let mut l = 0;
        let mut r = ss.len() - 1;
        while l < r {
            while l < r && !(ss[l].is_alphabetic() || ss[l].is_numeric()) {
                l += 1;
            }
            while l < r && !(ss[r].is_alphabetic() || ss[r].is_numeric()) {
                r -= 1;
            }
            if ss[l].to_ascii_lowercase() != ss[r].to_ascii_lowercase() {
                return false;
            }
            // 防止 usize 破界
            if r == 0 {
                return true;
            }
            l += 1;
            r -= 1;
        }
        true
    }
}