一个随机数算法

question:
suppose give a function Randomnized(1,N), it can generate from 1 to N random Integer number, pls use this function to accomplish a most effective program, it can generate 6 unduplicate nubmers.
answer:
publicclass RamdomNumber {

publicstaticvoid main(String[] args) {

int numbers[]=newint[50];

//add values to numbers array
for(int i=0;i<50 ;i++ )
{
numbers[i] = i+1;
}

int[] luckyNumbers = newint[20];

int i = 50;

for(int j = 0; j < 20; j++)
{
int index = (int)(Math.random()*(i-1));

System.out.println(index);
System.out.println("*************");
luckyNumbers[j] = numbers[index];

numbers[index] = numbers[numbers.length-j-1];

i--;
}

//output the values
for(int t = 0; t < 20 ; t++)
{
System.out.println(luckyNumbers [t]);
}
}

}