Java Data Structure #4

What I’ve Learned

First, I can simply multiply by 2 when turning decimal to integer.

Disclaimer

For LeetCode, I started learning about data structures on Udemy. I’ve been studying with lecture named Java Data Structures & Algorithms + LEETCODE Exercises.

LL: Remove Duplicates

Solution

I almost got building removeDuplicates(){}, but I’ve missed the last part. It was simple enough to think but, else part and temp = temp.next was difficult.

    public void removeDuplicates(){
        if(head == null) return;
        HashSet<Integer> hash = new HashSet<Integer>();
        Node before = null;
        Node temp = head;
        while(temp != null){
            if(hash.contains(temp.value)){
                before.next = temp.next;
                length--;
            } else{
                hash.add(temp.value);
                before = temp;
            }
            temp = temp.next;
        }
        
    }

LL: Binary to Decimal

My Solution

I’ve solved this problem. Using while loop. The idea of multipling 2 before moving to the next pointer was a good idea. I need to remember that algorithm for other time

   public int binaryToDecimal(){
        int num = 0;
        Node temp = head;
        
        while(temp != null){
            num += temp.value;
            if(temp.next == null)
                break;
            num *= 2;
            temp = temp.next;
        }
        return num;
    }

Solution

There was a simpler answer. Without using break, I can just multiply 2 and add the value in one line.

     public int binaryToDecimal() {
        int num = 0;
        Node current = head;
        while (current != null) {
            num = num * 2 + current.value;
            current = current.next;
        }
        return num;
    }