UVa 401 Palindromes (回文串与镜像串的综合判断)

Palindromes

Time Limit: 3000MS

Memory Limit: Unknown

64bit IO Format: %lld & %llu

Submit Status

Description

A regular palindrome is a string of numbers or letters that is the same forward as backward. For example, the string "ABCDEDCBA" is a palindrome because it is the same when the string is read from left to right as when the string is read from right to left.

 

A mirrored string is a string for which when each of the elements of the string is changed to its reverse (if it has a reverse) and the string is read backwards the result is the same as the original string. For example, the string "3AIAE" is a mirrored string because "A" and "I" are their own reverses, and "3" and "E" are each others' reverses.

A mirrored palindrome is a string that meets the criteria of a regular palindrome and the criteria of a mirrored string. The string "ATOYOTA" is a mirrored palindrome because if the string is read backwards, the string is the same as the original and because if each of the characters is replaced by its reverse and the result is read backwards, the result is the same as the original string.

Of course,"A","T", "O", and "Y" are all their own reverses.

A list of all valid characters and their reverses is as follows.

Character	Reverse	Character	Reverse	Character	Reverse
A	A	M	M	Y	Y
B		N		Z	5
C		O	O	1	1
D		P		2	S
E	3	Q		3	E
F		R		4
G		S	2	5	Z
H	H	T	T	6
I	I	U	U	7
J	L	V	V	8	8
K		W	W	9
L	J	X	X

Note that O (zero) and 0 (the letter) are considered the same character and therefore ONLY the letter "0" is a valid character.

Input

Input consists of strings (one per line) each of which will consist of one to twenty valid characters. There will be no invalid characters in any of the strings. Your program should read to the end of file.

Output

For each input string, you should print the string starting in column 1 immediately followed by exactly one of the following strings.

STRING	CRITERIA
" -- is not a palindrome."	if the string is not a palindrome and is not a mirrored string
" -- is a regular palindrome."	if the string is a palindrome and is not a mirrored string
" -- is a mirrored string."	if the string is not a palindrome and is a mirrored string
" -- is a mirrored palindrome."	if the string is a palindrome and is a mirrored string

Note that the output line is to include the -'s and spacing exactly as shown in the table above and demonstrated in the Sample Output below.

In addition, after each output line, you must print an empty line.

Sample Input

NOTAPALINDROME 
ISAPALINILAPASI 
2A3MEAS 
ATOYOTA

Sample Output

NOTAPALINDROME -- is not a palindrome.
 
ISAPALINILAPASI -- is a regular palindrome.
 
2A3MEAS -- is a mirrored string.
 
ATOYOTA -- is a mirrored palindrome.

Hint

use the C++'s class of string will be convenient, but not a must

题意:输入一个字符串,判断它是否为镜像串级回文串.输入的字符串保证不含数字0.

所谓镜像串, 是指左右镜像后原串相同,如 2S 和 3AIAE. 注意,并不是所有的字符在镜像之后都会得到一个合法 字符.

AC代码:

#include <cstdio>
#include <cstring>
#include <cctype>
const char *rev = "A   3  HIL JM O   2TUVWXY51SE Z 8 ";//空格分别为3,2,1,1,3,1,2,1
const char *msg[]= {
                    "not a palindrome",
                    "a regular palindrome",
                    "a mirrored string",
                    "a mirrored palindrome",
                   };

char r(char ch)
{
    if(isalpha(ch)) return rev[ch-'A'];
    return rev[ch-'0'+25];//前面有26个字母!?
}
int main()
{
    char s[30];
    while(scanf("%s",s) == 1)
    {
        int len = strlen(s);
        int p=1,m=1;
        for(int i=0;i<(len+1)/2;i++)//若为奇数,中间那个字符也要判断
        {
            if(s[i]!=s[len-1-i]) p=0;//不是回文串
            if(r(s[i])!=s[len-1-i]) m=0;//不是镜像串
        }
        printf("%s -- is %s.\n\n",s,msg[m*2+p]);
    }
}