LeetCode刷题-005最长回文子串

 1 string longestPalindrome(string s)
 2 {
 3     
 4     string str = "$#";
 5     for(int i = 0; i < s.size(); i++)   //字符串长度奇偶变换，添加‘$‘防止数组越界
 6     {
 7         str += s[i];
 8         str += "#";
 9     }
10     str += "$";
11     //cout<<str;
12  
13     int p[str.size()-2]={0};    //定义p[i]数组
14 
15     int right = 0, mid = 0;
16     for(int i = 1; i <  str.size()-1; i++)
17     {
18         if(right > i)
19         {
20             p[i] = (p[2*mid - i] < (right - i) ? p[2*mid - i] : (right - i));   //计算以i为中心的回文字串的最小长度
21         }
22         else
23         {
24             p[i] = 1;
25         }
26 
27         while(str[i - p[i]] == str[i + p[i]])  p[i]++;     //回文子串长度延伸
28         
29         if(i + p[i] > right)
30         {
31             right = i + p[i];
32             mid = i;
33         }
34 
35     }
36         
37     int max = 0, middle=0;
38     for(int i = 1; i < str.size()-1; i++)   //生成最终结果
39     {
40         if(p[i] > max)
41         {
42             middle = i;
43             max = p[i];
44         }
45     }