Duplicate array elements and unique elements

Question

So, i am writing a program that analyzes an entire array and displays the repeated values as well as the unique values:

int dupe = 0;
int[] range = {1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6};
for (int i = 0; i < range.length; i++) {
        for (int j = i + 1; j < range.length; j++) {
            if (range[i] == range[j]) {
                dup = range[j];
                System.out.println(dup);
            }
        }
}

The above code outputs the repeated values correctly but when the value repeats three or more times, it outputs that value many times instead of just once

1
2
2
2
3
3
3
6

How can i fix this?

For the unique value part of the program, i don't know where to start.

Thanks!

EDIT: The only Arrays class methods i can use are: binarySearch, copyOf, equals, fill, sort, and toString

I need to write my own implementation - not to use Set, HashSet etc. Or any other tools such as iterators

Answer 1

You can do somthing like bellow:

int[] range = {1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6};
boolean duplicate = false;
for (int i = 0; i < range.length; i++) {
     duplicate = false;
     for (int j = i + 1; j < range.length; j++) {
         if (range[i] == range[j]) {
             duplicate = true
         }
     }
     if(!duplicate){
         System.out.println(range[i]);
     }
}

Answer 2

You can add your values to Set. it will do all work for you.

int end = arr.length;
Set<Integer> set = new HashSet<Integer>();

for(int i = 0; i < end; i++){
    set.add(arr[i]);
}

If you cannot use other data structures, here is a good solution: https://stackoverflow.com/a/17974322/2290763

Answer 3

Other solution are correct but they will give O(n^2), you don't need to use two for loops. This will give you O(n)

    int[] range = {1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6};
    int temp = range[0];
    if(temp != range[range.length-1]){
     for (int i = 1; i < range.length; i++) {
            if(temp != range[i]){
               System.out.println(temp);
               temp = range[i];
           }
     }
    }
    else
       System.out.println(temp);

Answer 4

Each value in the array is either unique or occurs multiple times. There are no other cases. So your task can be stripped down to just remove the duplicates and print everything else. If the array is sorted then it is sufficient to just check against the last value while iterating to recognize duplicates.

I would do this:

int[] range = {1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6};
Arrays.sort(range);

for (int i = 0; i < range.length; i++) {
    if (i == 0) {
        System.out.println(range[0]);
    } else if (range[i - 1] != range[i]) {
        System.out.println(range[i]);
    }
}

Answer 5

Try after sorting the array:

int[] range = { 1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6 };
    Arrays.sort(range);
    System.out.println(range.length > 0 ? range[0]
            : "No sufficient elements");
    for (int i = 1; i < range.length; i++) {
        if (range[i - 1] != range[i]) {
            System.out.println(range[i]);
        }
    }

Answer 6

Edited. Try this:

    int[] range = { 1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6};
    for (int i = 0; i < range.length; i++) {
        int j = i + 1;
        for (; j < range.length && range[i] == range[j]; j++) {
            // do nothing
        }

        if (j >= i + 2) {
            System.out.println(range[i]);
            i = j;
        }

    }
}

The problem in your solution is int this part for (int i = 0; i < range.length; i++) { for (int j = i + 1; j < range.length; j++) {

For every element in array you are checking is there element with same value, and index is greater than index of element. For example, for element with index 2 (value 2) it's checking all (indexes: 3, 4, 5, 6, ...). And there are two matches (elements with index 3 and 4).

Edit: (After @FabianBarney comment)

Solution:

    String uni = "Uniques: ";
    String dup = "Duplicates: ";

    int[] range = { 1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 6};

    for (int i = 0; i < range.length; i++) {
        if (i + 1 < range.length && range[i + 1] == range[i]) {
            dup += range[i] + " ";

            int j = i + 1;
            while (j < range.length && range[i] == range[j]) {
                j++;
            }
            i = j - 1;
        } else {
            uni += range[i] + " ";
        }
    }

    System.out.println(uni);
    System.out.println(dup);