算法竞赛入门经典（第二版）第三章--回文字

 

c++

#include<iostream>
#include<string>
using namespace std;

//镜像需要一个检查表，常量数组,+35检查
char jian[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ123456789A000300HIL0JM0O0002TUVWXY51SE0Z0080";

int main()
{
 string s;
 while (getline(cin, s))
 {
  //来两个计数器：p记回文，m记镜像，p达到字符串长度一半表示是回文，m达到字符串全长表示是镜像，否则不然
  int p = 0, m = 0;
  //两个验证是可以同时进行，即p,m同时计数
  for (int i = 0; i < s.length(); i++)
  {
   //回文
   if (i <= s.length() / 2&&p==i)
   {
    if (s[i] == s[s.length() - 1 - i]) p++;
   }

   //镜像
   if (m == i)
   {
    for (int k = 0;; k++)
    {
     if (s[i] == jian[k])
     {
      if (s[s.length() - 1 - i] == jian[k + 35]) m++;
      break;
     }
    }
   }
  }
  //检查结束，开始判断,四种情况
  if (p >= s.length() / 2 && m== s.length()) cout << s << "--" << "is a mirrored palindrome";
  else if (p >= s.length() / 2) cout << s << "--" << "is a regular palindrome";
  else if (m == s.length()) cout << s << "--" << "is a mirrored string";
  else cout << s << "--" << "is not a palindrome";

  cout << endl;
 }
 system("pause");
 return 0;
}