思考人生中...

直接抄的…自己写的有点问题…放在下面

class Solution {
    
    
public:
    string longestPalindrome(string s) 
    {
    
    
        int i,j,p=0,l=0,n=s.size();
        for(i=0;i<n;i++)
        {
    
    
            for(j=1;j<=min(i,n-i);j++)
                if(s[i-j]!=s[i+j])  
                    break;
            if(l<j)
            {
    
    
                l=j;
                p=i;
            }
        }
        l--;
        int P=0,L=0;
        for(i=0;i<n;i++)
        {
    
    
            for(j=0;j<=min(i,n-i);j++)
                if(s[i-j]!=s[i+j+1])  
                    break;
            if(L<j)
            {
    
    
                L=j;
                P=i;
            }
        }
        L--;
        if(2*l+1>2*L+2) return s.substr(p-l,2*l+1);
        else            return s.substr(P-L,2*L+2);
    }
};

尝试暴力破解

class Solution {
    
    
public:
    bool testFx1(string x, int len) {
    
    
        //cout << "work" << x << len << endl;
        for (int r = 0, j = len; r < j; ++r, --j) {
    
    
            //cout << x[r] << "," << x[j] << endl;
            if (x[r] != x[j]) {
    
    
                //cout << x[r] << "," << x[j] << endl;
                return false;
            }
        }
        return true;
    }
/*
    string testFx2(string _In,  int _Begin_Point, int _End_Point) {
        string _Out;
        while (_Begin_Point <= _End_Point) {
            _Out.push_back(_In[_Begin_Point]);
            _Begin_Point++;
            //cout << _Out << endl;
        }
        return _Out;
    }
*/  
    string longestPalindrome(string s) {
    
    
        int size = s.size();
        if (size < 2) return s;
        int maxL = 1;
        while (s[maxL - 1] == s[maxL] && maxL < size) maxL++;
        string out = s.substr(0, maxL);
        for (int r = 0; r < size + 1; ++r) {
    
    
            for (int j = r + maxL; j < size; ++j) {
    
    
                //cout << "Ready for test" << r << ":" << s[r] << s[j] << endl;
                if (s[r] == s[j])
                    if (testFx1(s.substr(r,j+1), (j - r))) {
    
    
                        maxL = j - r + 1;
                        out = s.substr(r,j+1);
                        //cout << out << endl;
                    }
            }
        }
        //cout << out.size() << endl;
        if (out.front() != out.back()) out.pop_back();
        return out;
    }
};

问题出在重复尾缀…没有探明原因…
出错例如bbcccbbb等