Question

The following is a Java method that is part of a Linked List based Stack implementation:
void foo() {
if (front==null) return;
LinkedNode c = front;
int a = count/2;
for (int i=1; i<a; i++)
    c = c.next;
c.next = null;
}

Describe what this method is doing at a high level.

		Removing the last element
		Removing the upper half of elements in the Stack.
		Removing the first element
		Removing the bottom half of elements in the Stack.

Answer 1

Solution in BOLD:

Java code explanation:

void foo() {  
if (front==null)    /*Checks if the root is NULL or not*/

           return;   /* If List is empty return */
LinkedNode c = front; /*Take the front node of the list*/

int a = count/2;     /*Divide the node's count by 2 to find the middle node*/

for (int i=1; i<a; i++)   /*Traverse the list until middle node*/
    c = c.next;            /*Move the pointer to next node*/

c.next = null;       /*Make the node as NULL to Delete the mid-node..*/

} #end_of_foo

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Solution:

The Sample Linked list based stack implementation is as follows.

Top node - | 24 |

                   | 14 |

                   | 05 |      UPPER-HALF ELEMENTS

                   | 72 | <---------------------------------------------------->

                   | 96 |     BOTTOM-HALF ELEMENTS

                   | 45 |

Front node | 12 |  

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Since the list (stack) is traversed from the front to top node,

this method is removing "Removing the upper half of elements in the Stack".

Traversing up to the middle node(72) and making its next node as NULL, will remove the remaining nodes.

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