The Hardest Problem Ever
Time Limit: 1000MS | Memory Limit: 10000K | |
Total Submissions: 26502 | Accepted: 14358 |
Description
Julius Caesar lived in a time of danger and intrigue. The hardest situation Caesar ever faced was keeping himself alive. In order for him to survive, he decided to create one of the first ciphers. This cipher was so incredibly sound, that no one could figure it out without knowing how it worked.You are a sub captain of Caesar's army. It is your job to decipher the messages sent by Caesar and provide to your general. The code is simple. For each letter in a plaintext message, you shift it five places to the right to create the secure message (i.e., if the letter is 'A', the cipher text would be 'F'). Since you are creating plain text out of Caesar's messages, you will do the opposite:
Cipher text
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Plain text
V W X Y Z A B C D E F G H I J K L M N O P Q R S T U
Only letters are shifted in this cipher. Any non-alphabetical character should remain the same, and all alphabetical characters will be upper case.
Input
Input to this problem will consist of a (non-empty) series of up to 100 data sets. Each data set will be formatted according to the following description, and there will be no blank lines separating data sets. All characters will be uppercase.A single data set has 3 components:
- Start line - A single line, "START"
- Cipher message - A single line containing from one to two hundred characters, inclusive, comprising a single message from Caesar
- End line - A single line, "END"
Following the final data set will be a single line, "ENDOFINPUT".
Output
For each data set, there will be exactly one line of output. This is the original message by Caesar.Sample Input
START NS BFW, JAJSYX TK NRUTWYFSHJ FWJ YMJ WJXZQY TK YWNANFQ HFZXJX END START N BTZQI WFYMJW GJ KNWXY NS F QNYYQJ NGJWNFS ANQQFLJ YMFS XJHTSI NS WTRJ END START IFSLJW PSTBX KZQQ BJQQ YMFY HFJXFW NX RTWJ IFSLJWTZX YMFS MJ END ENDOFINPUT
Sample Output
IN WAR, EVENTS OF IMPORTANCE ARE THE RESULT OF TRIVIAL CAUSES I WOULD RATHER BE FIRST IN A LITTLE IBERIAN VILLAGE THAN SECOND IN ROME DANGER KNOWS FULL WELL THAT CAESAR IS MORE DANGEROUS THAN HE
Source
South Central USA 2002Regionals 2002 >> North America - South Central USA
问题链接:HDU1048 ThePOJ1298 ZOJ1392 UVALive2540Hardest Problem Ever。
问题简述:(略)
问题分析:以往,密码通信是一件重要的事情,是一项高技术的工作。不过译码的时候,通常是通过查密码本来实现的。这种方法依旧适用于现在这个计算机时代。
查表法仍然是一种好办法。有些程序员通过观察,找出编码规律,用程序来译码,程序没有通用性,不值得推荐和借鉴。
程序说明:译码过程,使用字符指针来处理,是一种好办法。先计算字符串长度,再用长度值来控制循环处理是一种倒腾。
简洁版AC的C语言程序如下:
/* HDU1048 The Hardest Problem Ever(简洁版) */
#include <stdio.h>
#include <string.h>
char start[]= "START";
char end[]= "END";
char endofinput[]= "ENDOFINPUT";
char cipher[] = "VWXYZABCDEFGHIJKLMNOPQRSTU";
int main(void)
{
char s[1024], *p;
for(;;) {
gets(s);
// 判断开始:START
if(strcmp(s, start) == 0)
continue;
// 判断报文结束:END
if(strcmp(s, end) == 0)
continue;
// 判断结束:ENDOFINPUT
if(strcmp(s, endofinput) == 0)
break;
// 译码
p = s;
while(*p) {
if('A' <= *p && *p <='Z') {
*p = cipher[*p - 'A'];
}
p++;
}
// 输出结果
printf("%s\n", s);
}
return 0;
}
严格语法版AC程序如下:
/* HDU1048 The Hardest Problem Ever */
#include <stdio.h>
#include <string.h>
char start[]= "START";
char end[]= "END";
char endofinput[]= "ENDOFINPUT";
char cipher[] = "VWXYZABCDEFGHIJKLMNOPQRSTU";
int main(void)
{
char s[1024], *p;
for(;;) {
gets(s);
// 判断结束:ENDOFINPUT
if(strcmp(s, endofinput) == 0)
break;
// 判断开始:START
if(strcmp(s, start) == 0) {
// START之后,END之前,需要处理多行
for(;;) {
gets(s);
// 判断报文结束:END
if(strcmp(s, end) == 0)
break;
// 译码
p = s;
while(*p) {
if('A' <= *p && *p <='Z') {
*p = cipher[*p - 'A'];
}
p++;
}
// 输出结果
printf("%s\n", s);
}
}
}
return 0;
}
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