最长回文串奇偶情况

Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.

class Solution {
public:
    string longestPalindrome(string s) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(s.empty() )
            return "";
        int imax = 0;
        int ileft=0, iright=0;
        for(int i=0; i<s.size(); ++i)
        {
            if(i-1>=0 )
            {
                if(s[i] == s[i-1])//even
                {
                    int ltmp=i-2, rtmp=i+1;
                    while(ltmp>=0 && rtmp<s.size() )
                    {
                        if(s[ltmp] != s[rtmp])
                            break;
                        --ltmp;
                        ++rtmp;
                    }
                    if(imax < rtmp-ltmp-1)
                    {
                        imax = rtmp-ltmp-1;
                        ileft = ltmp+1;
                        iright = rtmp-1;
                    }
                }
                //odd
                int ltmp=i-1,rtmp=i+1;
                while(ltmp>=0 && rtmp<s.size() )
                {
                    if(s[ltmp] != s[rtmp])
                        break;
                    --ltmp;
                    ++rtmp;
                }
                if(imax < rtmp-ltmp-1)
                {
                    imax = rtmp-ltmp-1;
                    ileft = ltmp+1;
                    iright = rtmp-1;
                }
            }
        }
        return s.substr(ileft,iright+1-ileft);
    }
};