Algorithm-linked list implementation stack

Source: Internet
Author: User

A linked list is a recursive data structure that is either empty (null), or just a reference to a node, a node that contains an object and a reference to another linked list, a node that may be an abstract corpse containing arbitrary data, and a node-only application that shows its role in the list. Compared to the array to have more flexibility, this article on a simple list to implement the stack, the biggest feature of the stack is LIFO, the queue is FIFO, the two are not the same, this article will be a simple implementation of OC stack.

Node Definition:

@interface node:nsobject@property  (strong,nonatomic)  nsstring  *value; @property  (Strong, nonatomic)  Node  *next; @end

Stack header file Definition:

@interface element @property  (strong,nonatomic) Node *first of stack:nsobject//stack top  , @property  (Assign, nonatomic) Nsinteger  count;-(BOOL) isempty;-(Nsinteger) size;-(void) Push: (NSString *) value;-(NSString *) pop;-( void) Remove: (NSString *) value; @end

There are three main implementation methods, into the stack (push), out of the stack (pop), delete (remove), it is important to note that the deletion of this article is a one-way list of the deletion, if the deletion of the last, time complexity and the length of the linked list is related, we can use a doubly linked list, interested can be studied.

Implementation code for the STACK.M:

@implementation stack-(BOOL) isempty{return self.count==0;} -(Nsinteger) size{return self.count;}    -(void) Push: (NSString *) value{Node *oldfirst=self.first;    Self.first=[[node Alloc]init];    Self.first.value=value;; self.count=self.count+1;}    -(NSString *) pop{if (!self.first) {return [NSString stringwithformat:@ "-1"];    } NSString *value=self.first.value;;    self.count=self.count-1; return value;}        -(void) Remove: (NSString *) value{if ([Self.first.value Isequaltostring:value]) {Node *node=self.first;        Node *;        Node.value=nextnode.value;;    self.count=self.count-1;        }else{Node *node=self.first;                    while ( {if ([ Isequaltostring:value]) {if ( {                    Node *;      ; }else{;                } self.count=self.count-1;            Break            }else{; }}} @end

Test code:

        Stack  *stack=[[stack Alloc]init];        Node *first=[[node Alloc]init];        [Email protected] "iOS technology group: 228407086";;        Stack.first=first;        [Stack push:@ "flyelephant"];        [Stack push:@ "blog Park"];        [Stack push:@ "Keso"];        [Stack remove:@ "flyelephant"];        NSLog (@ "Out of stack:%@", stack.pop);        NSLog (@ "Out of stack:%@", stack.pop);        NSLog (@ "Out of stack:%@", stack.pop);        NSLog (@ "Out of stack:%@", Stack.pop);

The effect is as follows:

Algorithm-linked list implementation stack

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