Palindromes

要注意：单个字符是没有对应反序串的。

几个测试：

NOTAPALINDROME -- is not a palindrome.

ISAPALINILAPASI -- is a regular palindrome.

2A3MEAS -- is a mirrored string.

ATOYOTA -- is a mirrored palindrome.

B -- is a regular palindrome.

E -- is a regular palindrome.

8 -- is a mirrored palindrome.

我用的 switch 结构：

/* UVa 401 */
# include <stdio.h>
# include <string.h>

# define MAXN 25

char s[MAXN], ss[MAXN];

char ch_map(char ch);
void s_map(char *s, char *ss);
int is_pal(char *s);

int main()
{
    int isPal, isMir, i;
    
    while (~scanf("%s", s))
    {
          for (i = 0; s[i] ; ++i)
              printf("%c", s[i]);
          s_map(s, ss);
          isPal = is_pal(s);
          isMir = is_pal(ss);
          if (strlen(s)==1 && ch_map(s[0])!=s[0]) isMir = 0;
          if (isPal && isMir) printf(" -- is a mirrored palindrome.\n");
          else if (isMir) printf(" -- is a mirrored string.\n");
          else if (isPal) printf(" -- is a regular palindrome.\n");
          else printf(" -- is not a palindrome.\n");
          printf("\n");
    }
    return 0;
}

char ch_map(char ch)
{
     switch (ch)
     {
            case 'E': return '3';
            case 'J': return 'L';
            case 'L': return 'J';
            case 'S': return '2';
            case 'Z': return '5'; 
            case '2': return 'S';
            case '3': return 'E';
            case '5': return 'Z';
            case 'A': case 'H': case 'I':
            case 'M': case 'O': case 'T':
            case 'U': case 'V': case 'W':
            case 'X': case 'Y': case '1':
            case '8':return ch;
            default : return '0';
     }
}

void s_map(char *s, char *ss)
{
     int i, len, L;
     len = strlen(s);
     L = len / 2;
     for (i = 0; i < L; ++i)
         ss[i] = s[i];   
     for ( ; s[i] ; ++i)
         ss[i] = ch_map(s[i]);
     ss[i] = '\0';
}

int is_pal(char *s)
{
    int i, len, L;
    len = strlen(s);
    L = len / 2;
    
    for (i = 0; i < L; ++i)
        if (s[i] != s[len-1-i]) return 0;
    return 1;
}