As we all know about the concept of stack, we can use arrays to implement the first, first, and foremost concepts. But the disadvantage of this implementation is that there is a limit on the quantity, we need to first define the size of this array. therefore, the emergence of the linked list solves the following problem: we need to insert and delete node data in the head of the linked list, because the time complexity of the header is at least O (1 ), if it is at the end, it is necessary to facilitate the tail position first, and then insert and delete, so that the time complexity is programmed O (n ). stack pressure: 1. create a node and direct it to the next node. point the top position of the current stack to the current node's output Stack: 1. get the current node element 2. obtain the next element 3 of the current node element. point the top of the stack to element 4 of the next node and return the node element obtained in step 1. The following is an implementation example/** <p> title: simple title </P> * <p> Description: A Brief Description </P> * <p> copyright: Copyright (c) </P> */
PackageStack;
Public
ClassNode {
PublicNode nextnode; // point to the next node
PublicOBJECT element; // The current object
PublicNode () {nextnode =
Null; Element =
Null;}
PublicNode (node, object element) {nextnode = node;
This. Element = element;}/*** sets the element and returns the original element *
@ ParamElement *
@ Return*/
PublicObject setele (object element) {object oldelement =
This. Element;
This. Element = element;
ReturnOldelement;}/*** get the current element *
@ Return*/
PublicObject getelement (){
ReturnElement;}/*** sets the current element and returns the original element */
PublicObject setelement (object element) {object OBJ =
This. Element;
This. Element = element;
ReturnOBJ;}/*** get the next node *
@ Return*/
PublicNode getnextnode (){
ReturnNextnode;}/*** set the next node *
@ ParamNextnode */
Public
VoidSetnextnode (node nextnode ){
This. Nextnode = nextnode; }}/ ** <p> title: simple title </P> * <p> description: </P> * <p> copyright: Copyright (c) </P> */package stack; public class Stack {public node top; // stack top element public int size; // stack size public stack () {Top = NULL; size = 0 ;} /*** number of elements in the stack * @ return */Public int size () {return size ;} /*** is the stack empty? * @ return */Public Boolean isempty () {return Top = NULL? True: false;}/*** get the top element of the stack * @ return */public object top () {return top. getelement ();}/**** output stack * @ return */public object POP () {If (isempty () {// you can create an exception class in this place, then throw system. out. println ("Stack is empty, cannot pop up"); return NULL;} object OBJ = top. getelement (); // Top = Top of the current element. getnextnode (); // update the size of the first node --; return OBJ;}/***** pressure stack * @ Param element */Public void push (object element) {node = new node (top, element); // create a node in the first part of the linked list and point to the next node Top = node; // set the current node as the stack header size ++ ;}}
