uva644 – Immediate Decodability

An encoding of a set of symbols is said to be immediately decodable if no code for one symbol is the prefix of a code for another symbol. We will assume for this problem that all codes are in binary, that no two codes within a set of codes are the
same, that each code has at least one bit and no more than ten bits, and that each set has at least two codes and no more than eight.

Examples: Assume an alphabet that has symbols {A, B, C, D}

The following code is immediately decodable:

A:01 B:10 C:0010 D:0000

but this one is not:

A:01 B:10 C:010 D:0000 (Note that A is a prefix of C)

Input 

Write a program that accepts as input a series of groups of records from a data file. Each record in a group contains a collection of zeroes and ones representing a binary code for a different symbol. Each group is followed by a single separator record containing
a single 9; the separator records are not part of the group. Each group is independent of other groups; the codes in one group are not related to codes in any other group (that is, each group is to be processed independently).

Output 

For each group, your program should determine whether the codes in that group are immediately decodable, and should print a single output line giving the group number and stating whether the group is, or is not, immediately decodable.

The Sample Input describes the examples above.

Sample Input 

0110001000009011001000009

Sample Output 

Set 1 is immediately decodableSet 2 is not immediately decodable

首碼編碼，由於資料很小直接窮舉每一種判斷即可，開始以為可以只判斷一半，但是因為判斷的時候有個長度的條件，所以相反的情況還是要判斷還是n*n次，不能n*n/2；

while (scanf("%s",&s[sum])==1)，scanf的傳回值是讀入值的個數，所以當沒有資料讀入時為0就結束了。後來用eof交了下也可以╮(╯▽╰)╭不能·太依賴別人的code。

#include <stdio.h>
#include <string.h>
void main ()
{char s[10][10];
 int num=0,l1,l2,flag,i,j,k,sum=0,a[10];
 while (scanf("%s",&s[sum])==1)
 {
  while (scanf("%s",&s[sum+1]))
  if (s[sum+1][0]=='9') break;
                   else ++sum;
  for (i=0;i<=sum;i++)
  a[i]=strlen(s[i]);
 
  for (i=0;i<=sum;i++)
  {
   for (j=0;j<=sum;j++)
   {flag=1;
 if ((i!=j)&&(a[j]>=a[i]))
 {for (k=0;k<a[i];k++)
  if (s[i][k]!=s[j][k]) {flag=0; break;}
 }
 else flag=0;
    if (flag) goto there ; 
   }
  }
  there : ;
  sum=0;
  ++num;
  if (flag) printf("Set %d is not immediately decodable\n",num);
       else printf("Set %d is immediately decodable\n",num);
 }
}