1 #include 
     
       2 using namespace std; 3  4 void substring(char* str) 5 {     6     int len = strlen(str); 7     len = 2*len + 1; 8     for(int i = len; i >= 1; i--) 9     {10         if(i%2 == 0)11             str[i-1] = str[i/2-1];12         else13             str[i-1] = '#';14     }15     str[len] = '\0';16     int* p = new int[len]; //p[i]用来保存第i个字符为中心的回文字串向右/向左扩张的距离17     int mx = 0; //表示已经处理的回文字串向右扩张的最长距离18     int id = 0; //表示上述回文子串的中间位置19     memset(p,0,len);20     for(int i = 0; i < len; i++)21     {22         if(mx - i > 0)23         {24             p[i] = p[2*id - i] < (mx - i)?p[2*id - i]:(mx-i);25         }26         else27             p[i] = 1;28         while(str[i + p[i]] == str[i - p[i]]) p[i]++;29         if(p[i] > mx - i)30         {31             mx = i + p[i];32             id = i;33         }34     }35     mx = 0;36     id = 0;37     for(int i = 0; i < len; i++)38     {39         if(p[i] > mx)40         {41             mx = p[i];42             id = i;43         }44     }45     cout<<"最长回文字串：";46     for(int i = id-mx+1; i < id+mx; i++)47     {48         if(str[i] != '#')49             cout<
      
       >str;62         substring(str);63         delete[] str;64         str = NULL;65     }66     return 0;67 }