Removing all duplicated numbers

[sr2cute702]

Hello,

could you help me fix my RemoveDuplicates method, its sopose to remove all numbers that were duplicated and not leave one.


this is my incorrect out put.

Initial List: 
12 4 25 6 4 -2 8 100 4 810 
Item to Delete: 4
List after removing all duplicates: 
12 810 25 6 4 -2 8 100

this is what has to show up.

Initial List: 
12 4 25 6 4 -2 8 100 4 810 
Item to Delete: 4
List after removing all duplicates: 
12 810 25 6 100 -2 8

#include <iostream>

using namespace std;

typedef int ItemType;

const int MAX_LENGTH = 100;

class List
{
        public:
                List();
                void Insert(ItemType item);
                void Delete(ItemType item);
                void ResetList();
                ItemType GetNextItem();
                int GetLength() const;
                bool IsEmpty() const;
                bool IsFull() const;
                bool IsThere(ItemType item) const;
                bool HasNext() const;
                void PrintForward() const;
                void PrintBackWard() const;
                void RemoveDuplicates(ItemType);
                int GetLocation(ItemType);
        private:
                int length;
                int currentPos;
                ItemType data[MAX_LENGTH];
};

int main()
{
        List L1;
        int n, x;
        cin>>n;
        for (int i = 0; i < n; i++)
        {
                cin>>x;
                L1.Insert(x);
        }

        int m;
        cin >> m;

        cout<<"Initial List: "<<endl;
        L1.PrintForward();
        cout<<"Item to Delete: "<< m << endl;
        cout<<"List after removing all duplicates: "<<endl;
        L1.RemoveDuplicates(m);
        L1.PrintForward();

        return 0;

}

List::List()
{
        length = 0;
        currentPos = 0;
}

bool List::IsEmpty() const
{
        return (length == 0);
}

bool List::IsFull() const
{
        return (length == MAX_LENGTH);
}

int List::GetLength() const
{
        return length;
}

void List::Insert(ItemType item)
{
        data[length] = item;
        length++;
}

void List::Delete(ItemType item)
{
        int index = 0;
        while (index < length && item != data[index])
                index++;
        if (index < length)
        {
                data[index] = data[length - 1];
                length--;
        }
}

bool List::IsThere(ItemType item) const
{
        int index = length - 1;
        while (index >= 0 && item != data[index])
                index--;
                return (index >= 0);
}

void List::ResetList()
{
        currentPos = 0;
}

bool List::HasNext() const
{
        return (currentPos != length);
}

ItemType List::GetNextItem()
{
        ItemType item;
        item = data[currentPos];
        currentPos++;
        return item;
}

void List::PrintForward() const  

{
        int i = 0;
        if (IsEmpty())
        {
                cout<<"List is Empty"<<endl;
                return;
        }
        while (i<length)
        {
                cout<<data[i]<<" ";
                i++;
        }
        cout<<endl;
}

void List::PrintBackWard()const
{
        int i = length;
        if (IsEmpty())
        {
                cout<<"List is Empty"<<endl;
                return;
        }
        while (i>0)
        {
                cout<<data[i-1]<<" ";
                i--;
        }
        cout<<endl;
}

int List::GetLocation(ItemType item)
{
        int index = 0;
        while (item != data[index])
                index++;
        return index;
}

void List::RemoveDuplicates(ItemType item)
{



        
        int index = 0;
        while (index < length && item != data[index])
        {
                index++;
                
                if (index < length && item == data[index] )
                {
                        data[index] = data[length - 1];
                        length--;
                
                }
                
        }

        
}

[Jaybob66]

@line 90,91 you take the last item from the list and use it to overwrite the item you are deleting, this changes the order of the items in the list.

My suggestion is to modify List::DeleteItem() to take an index (so maybe rename to DeleteAt(int index))
In this routine shuffle all items up the list to close the gap where the deleted item was.

int lastIndex = length - 1;
while (index < lastIndex) {
    data[index] = data[index+1];
}
--length;

also at line 157, index needs to default to -1 so that you return an invalid index if the item is not found.

then List::RemoveDuplicates() can look like this...

do {
    int i = GetLocation(item);

    if (i != -1) {
        DeleteAt(i);
    }
} while (i != -1);