Interview 150
Palindrome Number
- Problem
- LC 9
- File
- interview150_LC9PalindromeNumber.java
- Path
- pkg5leetcode/interview150/interview150_LC9PalindromeNumber.java
- Package
- pkg5leetcode.interview150
- Command
- java pkg5leetcode/interview150/interview150_LC9PalindromeNumber.java
- Approach
- Reverse half of digits; compare with remaining half.
- Complexity
- Time O(log n), Space O(1)
There is no in-browser runner. This is the file from the curriculum, unchanged.
1package pkg5leetcode.interview150;2 3/*4 * Palindrome Number | LC 95 * APPROACH: Reverse half of digits; compare with remaining half.6 * COMPLEXITY: Time O(log n), Space O(1)7 */8public class interview150_LC9PalindromeNumber {9 static boolean isPalindrome(int x) {10 if (x < 0 || (x % 10 == 0 && x != 0)) return false;11 int rev = 0;12 while (x > rev) {13 rev = rev * 10 + x % 10;14 x /= 10;15 }16 return x == rev || x == rev / 10;17 }18 19 public static void main(String[] args) {20 check(isPalindrome(121), "case1");21 check(!isPalindrome(-121), "case2");22 check(!isPalindrome(10), "case3");23 System.out.println("all tests passed");24 }25 26 static void check(boolean cond, String name) {27 if (!cond) throw new AssertionError("FAILED: " + name);28 System.out.println(" PASS " + name);29 }30}