《算法竞赛入门经典2ndEdition 》例题3-3 回文词(Palindromes, Uva401)

好吧，这道题真心写了很长时间（不得不承认我很弱），现在还有一个程序没改出来，贴出来希望各位大神能给我挑挑错，下面这个是没有AC的代码：

#include <cstdio>#include <cstring>#include "string.h"char s[30];using namespace std;bool check_palindrome();bool check_mirrored(int, int);int main(){  //freopen("New Text Document.txt","r",stdin);  //freopen("Output.txt","w",stdout);  while(scanf("%s", s) != EOF)  {    int n = strlen(s);    printf("%s ", s);    if(check_palindrome())// a palindrome    {      int flag = 1;      for(int i = 0; i <= n/2; i++)//=        if(!check_mirrored(i,n-i-1))         {          flag = 0;          printf("-- is a regular palindrome.\n");          break;        }      if(flag == 1) printf("-- is a mirrored palindrome.\n");    }    else//not a palindrome    {      int flag = 1;      for(int i = 0; i <= n/2; i++)//=        if(!check_mirrored(i,n-i-1))         {          flag = 0;          printf("-- is not a palindrome.\n");          break;        }      if(flag == 1) printf("-- is a mirrored string.\n");    }    printf("\n");  }  //getchar();getchar();  return 0;} bool check_palindrome(){  int n = strlen(s);  for(int i = 0; i < n/2; i++)    if(s[i] != s[n-i-1]) return false;  return true;}bool check_mirrored(int x,int y){  char a = s[x], b = s[y];  if(a == b)    switch(a)    {      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 true;      //default:return false;    }  else  {    if(a > b)     {      char ch;      ch = a; a = b; b = ch;    }     switch(a)    {      case '2':           if(b == 'S') return true;           else return false;      case '3':           if(b == 'E') return true;           else return false;      case '5':           if(b == 'Z') return true;           else return false;      case 'J':           if(b == 'L') return true;           else return false;      //default: return false;    }    return false;  }}

下面这个是看了书之后使用常量数组简化了一下check_mirrored函数，就AC了，但目前还没找到上个程序的错误。

#include <cstdio>#include <cstring>char s[30];const char* rev = "A   3  HIL JM O   2TUVWXY51SE Z  8 ";bool check_palindrome();bool check_mirrored();int main(){  //freopen("New Text Document.txt","r",stdin);  //freopen("Output.txt","w",stdout);  while(scanf("%s", s) != EOF)  {    printf("%s ", s);    if(check_palindrome())// a palindrome      if(!check_mirrored())         printf("-- is a regular palindrome.\n");      else printf("-- is a mirrored palindrome.\n");    else//not a palindrome      if(!check_mirrored())           printf("-- is not a palindrome.\n");        else printf("-- is a mirrored string.\n");    printf("\n");  }  //getchar();getchar();  return 0;} bool check_palindrome(){  int n = strlen(s);  for(int i = 0; i <= n/2; i++)    if(s[i] != s[n-i-1]) return false;  return true;}bool check_mirrored(){  int n = strlen(s);  for(int i = 0; i <= n/2; i++)    if(s[i]<='Z' && s[i]>='A' && *(rev+s[i]-'A')==s[n-i-1]) continue;    else if(s[i]<='9' && s[i]>='1' && *(rev+s[i]-'1'+26)==s[n-i-1]) continue;    else return false;  return true;}

虽然AC了，但还是觉得没有Rujia Liu给出的代码简洁，下面这个是从书配套的代码仓库下载的代码。
https://github.com/aoapc-book/aoapc-bac2nd/blob/master/ch3/UVa401.cpp

// UVa401 Palindromes// Rujia Liu#include<stdio.h>#include<string.h>#include<ctype.h>const char* rev = "A   3  HIL JM O   2TUVWXY51SE Z  8 ";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];}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++) {      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]);  }  return 0;}