9. Palindrome Number

key points

  • negative numbers
  • overflow
  • no extra space

The break point is sum >= x –> (sum ==x)||(sum/10==x)

source code

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public boolean isPalindrome(int x) {
    if(x < 0 || (x!=0 && x%10==0)){
        return false;
    }
    int sum = 0;
    while(x > sum){
        sum = x%10 + sum*10;
        x/=10;
    }
    return (sum ==x)||(sum/10==x);
}