[Leetcode] Longest palindromic Substring

Problem Description:

Given a string S, find the longest palindromic substring ins. The maximum length of S is assume, and there exists one unique longest palindromic substring.

Basic idea:

The Navie solution of the subject is to test if each (I,J) i<=j is a palindrome, and record the maximum condition. O (n^3)

If you look both ways from the center of a palindrome, you only need the complexity of O (n^2). This method is to determine each point as a palindrome string, and record and maintain the longest back text string. For ease of handling, you can insert a special character "#" in each of the two characters in a string, so that the processing of even palindrome strings and odd palindrome strings can be Fu Yi together.

Code:

   Public String Longestpalindrome (string s) {  //java        if (s.length () <= 1)            return s;                    String tmpstr = "#";        for (int i = 0; I <s.length (); i++)            tmpstr + = S.charat (i) + "#";                String max = "";        for (int i = 1; i<tmpstr.length ()-1; i=i+1) {            int toleft = i-1;            int toright = i+1;            while (ToLeft >=0 && toright <tmpstr.length ()) {                if (tmpstr.charat)! = ToLeft (Tmpstr.charat) ) Break                    ;                else {                    toleft--;                    toright++;                }            }            if (Toright-toleft-2 > Max.length ())                max = tmpstr.substring (toleft+1,toright);        }        Return Max.replaceall ("#", "");    }

[Leetcode] Longest palindromic Substring