POJ 1226 (longest public substrings with Reverse Order)

Substrings
Time Limit: 1000 MS Memory Limit: 10000 K
Total Submissions: 9639 Accepted: 3319
Description
Find the longest 'positive/inverse 'substring of some strings so that it is the substring of all strings (even in reverse order ).
Input
Number of first behavior data t, (1 <=t <= 10 ),
For each group of data, the number of first behavior strings is n (1 <= n <= 100), and the next n behavior strings (length cannot exceed 100 ).
Output
Each row has one number, indicating the length of the longest 'positive/inverse 'substring.
Sample Input
2
3
ABCD
BCDFF
BRCD
2
Rose
Orchid
Sample Output
2
2
Source
Tehran 2002 Preliminary
Or KMP, first enumerate the string in the first string, and then check whether it is a 'positive/inverse 'substring of other strings.

[Delphi]
Program P1226;
Const
Maxn = 100;
Maxt = 10;
Var
Tt, n, m, I, j, k, ans: longint;
Flag: boolean;
A: array [1 .. maxn] of string;
P: string;
Next: array [1 .. maxn] of longint;
 
Function kmp (a, B: string): boolean;
Var
I, j, n, m: longint;
Begin
I: = 1; j: = 0; next [1]: = 0;
N: = length (a); m: = length (B );
While (I <m) do
Begin
If (j = 0) or (B [I] = B [j]) then
Begin
Inc (I); inc (j );
If (B [I] <> B [j]) then next [I]: = j else next [I]: = next [j];
End else j: = next [j];
End;
 
I: = 0; j: = 0;
While (I <= n) and (j <= m) do
Begin
If (j = 0) or (a [I] = B [j]) then
Begin
Inc (I); inc (j );
End else j: = next [j];
End;
If (j> m) then exit (true );
Exit (false );
End;
Function ob_s (a: string): string;
Var
I, j, n: longint;
Begin
 
Ob_s: = ''; n: = length ();
For I: = n downto 1 do ob_s: = ob_s + a [I];
End;
Function compare (a, B: string): boolean;
Var
N, m: longint;
Begin
N: = length (a); m: = length (B );
If (n <> m) then exit (n <m );
For I: = 1 to n do
If a [I] <> B [I] then exit (a [I] <B [I]);
Exit (false );
End;
 
 
Begin
Readln (tt );
While (tt> 0) do
Begin
Ans: = 0;
Readln (n );
For I: = 1 to n do readln (a [I]);
 
For I: = 1 to length (a [1]) do
For j: = I to length (a [1]) do
Begin
P: = copy (a [1], I, j-I + 1 );
Flag: = true;
For k: = 2 to n do
Begin
If not (kmp (a [k], p) or kmp (a [k], ob_s (p) then
Begin
Flag: = false; break;
End; www.2cto.com
End;
If flag and (length (p)> ans) then ans: = length (p );
 
 
End;
 
Writeln (ans );
Dec (tt );
End;
End.