UVA 401 回文词 刘汝佳紫书

版权声明：那个，最起码帮我加点人气吧，署个名总行吧 https://blog.csdn.net/qq_41670466/article/details/82588249

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(ifithasareverse)andthestringisreadbackwardstheresultisthesameastheoriginalstring. 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.

分析：这里紫书上的方法很精简，对刘汝佳更加的佩服；对于镜像的处理是先进行预处理，预先储存好存在镜像单词的镜像，然后直接查询；

代码：

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<ctype.h>

using namespace std;
const char*  rev = "A   3  HIL JM O   2TUVWXY51SE Z 8 ";
const char * msg[] = { "is not a palindrome.","is a regular palindrome.","is a mirrored string.","is a mirrored palindrome." };

char r(char ch)
{
	if (isalpha(ch))		return rev[ch - 'A'];
	return		rev[ch - '0' + 25];
}

int main()
{
	char s[30];
	while (scanf("%s", s) !=EOF)
	{
		int len = strlen(s);
		int p = 1, m = 1;
		for (int i = 0; i < (len + 1) / 2; i++)
		{
			if (s[i] != s[len - 1 - i])  p = 0;
			if ( r( s[i] ) != s[len - 1 - i])	m = 0;
		//	if (p == 0 && m == 0) break;
		}
		printf("%s -- %s\n\n", s, msg[m * 2 + p]);
	}
	//system("pause");
	return 0;
}