Leetcode:palindrome number-Palindrome

1. Title

Palindrome Number (palindrome)

2. Address of the topic

Https://leetcode.com/problems/palindrome-number

3. Topic content

English: Determine whether an integer is a palindrome. Do this without extra space.

English: Confirm whether an integer is a palindrome number

4. Method of solving Problems 1

After the number is flipped to determine whether the original number is equal, you can refer to Leetcode 7th (Reverse Integer) problem-solving ideas. The Java code is as follows:

/** *  function Description:leetcode 9 - palindrome number *  developer:tsybius *  Development Date: September 24, 2015  */public class solution {        / **     *  determine if a number is a palindrome      *  @param  x  number      *  @return  true: Yes, false: No      */     public boolean ispalindrome (int x)  {                 //negative number cannot be a palindrome          if  (x < 0)  {             return false;        }                 //reversal number observation is equal          if  (X&nbsP;== reverse (x))  {            return  true;        } else {             return false;        }     }        /**     *   Invert digital      *  @param  x  reversed Digital      * @ return  Inverted number      */    public int reverse (int &NBSP;X)  {                 long result = 0;        while  (x!=0)  {             result = result *  10 + x % 10;            x /= 10;         }                 return  (result > integer.max_value | |  result < integer.min_value)  ? 0 :  (int) result;    } }

5. Method of solving Problems 2

Another method is to convert a number to a string and then reverse the string with the StringBuilder class to determine whether the two strings are equal. The Java code is as follows:

/** *  function Description:leetcode 9 - palindrome number *  developer:tsybius *  Development Date: September 24, 2015  */public class solution {        / **     *  determine if a number is a palindrome      *  @param  x  number      *  @return  true: Yes, false: No      */     public boolean ispalindrome (int x)  {         if  (x < 0)  return false;        if   (X&NBSP;&LT;&NBSP;10)  return true;                 string str1 = string.valueof (x);         String str2 =  (New stringbuilder (STR1)). Reverse (). toString ();                  if  (Str1.equals (str2))  {             return true;         } else {             return false;        }    }}

6. Method of solving Problems 3

Another way is to convert directly to a string, and then compare the character of the string symmetric position separately. The Java code is as follows:

/** *  function Description:leetcode 9 - palindrome number *  developer:tsybius *  Development Date: September 24, 2015  */public class solution {        / **     *  determine if a number is a palindrome      *  @param  x  number      *  @return  true: Yes, false: No      */     public boolean ispalindrome (int x)  {         if  (x < 0)  return false;        if   (X&NBSP;&LT;&NBSP;10)  return true;                 string str = string.valueof (x);         for  (Int i = 0; i < str.length ()  / 2;  i++)  {            if  (Str.charat (i)  !=  Str.charat (Str.length ()  - i - 1))  {                 return false;             }         }                 return true;     }}

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Leetcode:palindrome number-Palindrome