我应该如何实现删除我的自定义链接列表的最右半部分

Question

Write the method removeRightmostHalf member of the class LinkedList . Do not call any methods of the class and do not use any auxiliary data structures.

If l contains A! B! C! D! E A! B! C! D! E A! B! C! D! E , then after calling l.removeRightmostHalf() , l becomes A! B! C A! B! C A! B! C .

int size = 0 ; 
int halfSize = 0;
current = head;
while (current.next != null) {
    ++size;
    current=current.next;
}
++size;

if (size % 2 == 0) {
    halfSize = (size / 2);
    for (int i = halfSize + 1; i < size; i++) {
    }
}

I do not know how I will remove inside for loop. Any help!

Answer 1

I would suggest you to use two pointers, slow and fast pointer. Initially both will be pointing to the start of the linked list.

• The slow pointer will move one node at a time.
• The fast will move two node a time.

The moment you see that fast pointer has reached the end of the list, just mark the slow pointer node as end of the list, by setting next=null ;

Important note that, the discovery of the end of the list will be depend on the even/odd size of the list. So design and test with both cases.

Answer 2

This will work , when you reach the half of the list just cut the link with the rest of it.

public void removeRightMost() {
    int size = 0;
    int halfSize = 0;
    current = head;

    while (current!= null) {
        size++;
        current = current.next;
    }

    if (size % 2 == 0) {
        halfSize = (size / 2);

        int count = 0;
        current = head;

/* if the number of elements is even you need to decrease the halfSize 1 because 
you want the current to reach the exactly half if you have 4 elements the current
should stop on the element number 2 then get out of the loop */

       while (count < halfSize-1) { 
            current = current.next;
            count++;
        }
        current.next=null;      //here the process of the deletion when you cut the rest of the list ,  now nothing after the current (null)
    }

    else {
        halfSize = (size / 2);

        int count = 0;
        current = head;
        while (count < halfSize) {
            current = current.next;
            count++;
        }
        current.next=null;
    }

    current=head;  // return the current to the first element (head)
}

good luck