Leetcode 125. Valid palindrome-----java

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

For example,
"A man, a plan, a canal: Panama"is a palindrome.
"race a car"is not a palindrome.

Note:
Are you consider that the string might is empty? This was a good question to ask during a interview.

For the purpose of this problem, we define empty string as valid palindrome.

Read whether a string is a palindrome string (only the characters and numbers in the period are judged).

1, two stacks, from front to back and back forward, and then determine whether two stacks are the same.

 Public classSolution { Public BooleanIspalindrome (String s) {Stack stack1=NewStack<character>(); Stack Stack2=NewStack<character>(); S=s.tolowercase (); Char[] Word =S.tochararray (); intLen =s.length ();  for(inti = 0;i<len;i++){            if((Word[i] >= ' 0 ' && word[i] <= ' 9 ') | | (word[i]>= ' A ' && word[i]<= ' z ') ) Stack1.push (Word[i]); if((Word[len-1-i] >= ' 0 ' && word[len-1-i] <= ' 9 ') | | (word[len-1-i]>= ' A ' && word[len-1-i]<= ' z ')) Stack2.push (Word[len-i]); }        returnstack1.equals (STACK2); }}

2, directly with two pointers to record left and right can be.

 Public classSolution { Public BooleanIspalindrome (String s) {Char[] Word =s.tolowercase (). ToCharArray (); intLen =s.length (); intleft = 0,right = Len-1;  while(Left <Right ) {            if( ! ((Word[left] >= ' 0 ' && word[left] <= ' 9 ') | | (word[left]>= ' A ' && word[left]<= ' z ')) ) left++; Else if( ! ((Word[right] >= ' 0 ' && word[right] <= ' 9 ') | | (word[right]>= ' A ' && word[right]<= ' z ' )) right--; Else if(Word[left] = =Word[right]) { Left++; Right--; }Else                return false; }        return true; }}

Leetcode 125. Valid palindrome-----java