LeetCode Palindrome Number Solution Explained - Java

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[akhila]

This is the first time I am coming across such a beautiful solution of Palindrome Number

[krypton]

For those who didn't understand why x%10 === 0 is checked in Line 7:
Try a dry run with test case x=10 or x as a multiple of 10. The x and rev values will be reversed from what is expected.

[smithcodes]

That is an elegant solution. What I used to do was just reverse the string array and compare those two arrays. The run time obviously was pretty bad.

[saylik]

Line 3 (correction) : if (x>=0 && x<=9){return true;}

[beka]

public boolean isPalindrome(int x) {
String str = Integer.toString(x);
int left = 0;
int right = str.length() - 1;

while (left < right) {
if (str.charAt(left) != str.charAt(right)) {
return false;
}
left++;
right--;
}

return true;
}
This is much more cleaner

[msugal]

Hey nick why did you check in the second if statement if (x < 0 || x % 10 == 0) why is the x % 10 needed here?

[mohammedghabyen]

string intStr = x.ToString();
int left = 0;
int right = intStr.Length-1;

while(left<right){


return false;
left++;
right--;
}
return true;

[tanmaysingal]

Won't reversing integers this way be susceptible to integer overflows? Like what if the original number is less that the MAX_INT but when you reverse it, it goes over MAX_INT value?

[momentumbees]

public class PalindromeNumber {
public static boolean isPalindrome(int number) {
if (number < 0) {
return false; // Negative numbers cannot be palindromes
}

int reversedNumber = 0;
int originalNumber = number;

while (number > 0) {
int digit = number % 10;
reversedNumber = reversedNumber * 10 + digit;
number /= 10;
}

return originalNumber == reversedNumber;
}

public static void main(String[] args) {
int number = 12321;

if (isPalindrome(number)) {
System.out.println(number + " is a palindrome number.");
} else {
System.out.println(number + " is not a palindrome number.");
}
}
}

[souravsaha]

Try to explain well, I mean for the base cases that u take in the program. No hurry /''you know''. There are lot of people who didn't get there answers 😂.

[tfh]

going from edabit very easy to leetcode easy is like going from hell to mt everest omg.

[exactly]

No presented solution before coding so it is completely not understandable what's going on.

[shaunhyp]

Isn’t this still checking the entire int since it’s reversing the number and comparing if they equal once x <= reversed_int?

[sivaayyappakumarbuddi]

I don't understand x == reversed_int/10 included in the if statement apart from x == reversed_int(Line 20)

[davidzenteno]

so reversed_int is 0 on line 11, on line 16 will it always be (0 * 10) + pop? I am confused on this part. Won't reversed_int always equal pop?

[sangramgotke]

you are comparing( x== reversed_int); how this is equal mann?here reversed _int is half of the X, or always less, , think of this line20;

[wenkaiyang]

unfortunately, you did not explain anything but read through the entire script. not very helpful. very disappointing.

[alpacas]

does anyone know why he set while (x > reverse_int) instead of (x != 0)? at first I thought it would just be faster but I tried it both ways and x != 0 doesn't even work

[RaymondStormblssed]

that does not look like an easy problem tbh

[itech]

x%10 == 0 doesn't always work, for x = 0 for example it returns 0 but 0 is a palindrome (at least if you consider that single digit nums are palindromes) no?