如何从阵列中删除重复项？

Question

I am trying to make is so that in the method populate as the populate array increases it checks the index above if the value is the same. However, I have no idea how to do it without going through each index individually making it super inefficient. I tried to make a for loop where the I value is 0 and increases by 1 and inside that for loop is another for loop with the b value is 1 and that also increases by 1. Inside the second for loop I have an if statement and if the I index is equal to the b index the I index is revalued again

public class CH7Ass {

    public static void main(String[] args) {
        int user;
        int[] array;
        int checkUserNum;
        int tries=0;
        System.out.println("I bet you can't guess my six numbers");     
        array=populate();
        do{
            tries++;
            user=getUserNum();
            checkUserNum=checkUserNum(user,array);
            array=removeFromArray(array,checkUserNum);
        }while(tries<6);
    }

    public static int[] populate(){
        int[] populate;
        populate= new int [6];
        int random;

        for(int i=0;i<populate.length;i++){
            random=(int) ((Math.random())*50);      //goes from 0-49
            populate[i]=random;
            System.out.println(populate[i]);
            for(int b=1;b<populate.length;b++){
                if(populate[b]==populate[i]){
                    populate[i]=random;
                }
            }
        }
        return  populate;
    }


    public static int getUserNum(){
        int getUserNum;

        do{
            System.out.println("Please input a number from 1 to 49:");
            getUserNum=TextIO.getInt();
        }while((getUserNum<1)||(getUserNum>49));

        return getUserNum;
    }

    public static int checkUserNum(int getUserNum,int[] array){
        boolean check=false;
        int checkUserNum = 0;
        for(int i=0;i<array.length;i++){
            if(array[i]==getUserNum){
                check=true;
                System.out.println("You got it");
                checkUserNum=i;
            }
        }
        if(check==false){
            checkUserNum=-1;
            System.out.println(checkUserNum);
        }

        return checkUserNum;
    }


    private static int[] removeFromArray(int[] array,int checkUserNum){
        int[] removeFromArray;
        if(checkUserNum!=-1){
            array[checkUserNum]=0;
            removeFromArray=array[checkUserNum];
        }
        return removeFromArray;
    }
}

Answer 1

I am by no means an expert in algorithms, but I think one simple and easy to implement modification you could make would be the following.

At each iteration of your algorithm, instead of starting the inner loop at b = 1 , you could start it at b = i + 1 . This would yield an equivalent result since, if you are at index i of the outer loop, you have already compared all indexes smaller than i with the rest of the array.

Answer 2

You could do it by setting up some min max values that increase as your for loop works. That way you set boundaries for the random number and force them to be within different boundaries.

public static int[] populate(){
   int[] populate = new int [6];
   int random = 0;
   double maximum = 0.0;
   for(int i=0;i<populate.length;i++){
      maximum += ( 50 / 6 ); 
      random =   ( Math.random()  *  (  maximum  - (8 * i )  ) +  (8 * i ) ) ;      
      populate[i] = random;
   }
   return  populate;
}