A Practical Introduction to Data Structures and Algorithm Analysis

Sec. 4.1 Lists 115// Singly linked list node with freelist supportclass Link {private E element; // Value for this nodeprivate Link next; // Point to next node in list// ConstructorsLink(E it, Link nextval){ element = it; next = nextval; }Link(Link nextval) { next = nextval; }Link next() { return next; }Link setNext(Link nextval){ return next = nextval; }E element() { return element; }E setElement(E it) { return element = it; }// Extensions to support freelistsstatic Link freelist = null; // Freelist for the class// Get new linkstatic Link get(E it, Link nextval) {if (freelist == null)return new Link(it, nextval); // Get from "new"Link temp = freelist;// Get from freelistfreelist = freelist.next();temp.setElement(it);temp.setNext(nextval);return temp;}void release() {element = null;next = freelist;freelist = this;}} // class Link// Return Link to freelist// Drop reference to the elementFigure 4.11 Implementation for the Link class with a freelist. The staticdeclaration for member freelist means that all Link class objects share thesame freelist pointer variable instead of each object storing its own copy.In the implementation shown here, the link class is augmented with methodsget and release. Figure 4.11 shows the reimplementation for the Link class tosupport these methods. Note how simple they are, because they need only removeand add an element to the front of the freelist, respectively.The freelist methods get and release both run in Θ(1) time, except in thecase where the freelist is exhausted and the new operation must be called.