2013
11-12

# Reduced ID Numbers

T. Chur teaches various groups of students at university U. Every U-student has a unique Student Identification Number (SIN). A SIN s is an integer in the range 0 ≤ s ≤ MaxSIN with MaxSIN = 106-1. T. Chur finds this range of SINs too large for identification within her groups. For each group, she wants to find the smallest positive integer m, such that within the group all SINs reduced modulo m are unique.

On the first line of the input is a single positive integer N, telling the number of test cases (groups) to follow. Each case starts with one line containing the integer G (1 ≤ G ≤ 300): the number of students in the group. The following G lines each contain one SIN. The SINs within a group are distinct, though not necessarily sorted.

For each test case, output one line containing the smallest modulus m, such that all SINs reduced modulo m are distinct.

2
1
124866
3
124866
111111
987651


1
8


//* @author  mekarlos@gmail.com
import java.util.Hashtable;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Hashtable< Integer,Integer> table;
Scanner scan=new Scanner(System.in);
int M[]=new int[300];
int n=scan.nextInt(),k=0,m=1;
boolean band=false;
for(int i=0;i< n;i++){
k=scan.nextInt();
band=true;
table=new Hashtable< Integer, Integer>();
for(int j=0;j< k;j++){
M[j]=scan.nextInt();
}
m=k;
while(true){
band=true;
for(int j=0;j< k;j++){
if(table.get((M[j]%m))==null){
table.put((M[j]%m), 0);
}
else {
band=false;
break;
}
}
if(band==true) break;
table.clear();
m++;
}
System.out.println(m);
}
}
}