异或链表原理及实现

异或链表，时间换空间思想的应用，一种双向链表的实现方式，在链表节点地址域中只有前后节点地址的异或值，计算下一个节点时，可以用上一节点的地址和当前节点的地址域中的值进行异或操作，即可获取下一节点的地址值。

#include <iostream>

// XOR Node
class XORNode {
public:
    int data;
    XORNode *xor_with_next;

    XORNode(int value, XORNode * xor_val) : data(value), xor_with_next(xor_val) {}
    XORNode(){
	}
};

// XOR Linked List
class XORLinkedList {
private:
    XORNode* head;
    XORNode* tail;

public:
    XORLinkedList(){
    	head =new XORNode();
    	head->data=0;
    	tail = new XORNode();
    	tail->data=0;
    	tail->xor_with_next = head;
    	head->xor_with_next = tail;
	}

    // 添加新节点
    void append(int value) {
    	std::cout<<"inset "<<value<<std::endl;
    	if(head->xor_with_next==tail){
    		XORNode* newNode = new XORNode(value, (XORNode *)(((unsigned long long)head)^((unsigned long long)tail)));
    		head->xor_with_next=(XORNode *)(((unsigned long long)newNode^(unsigned long long)tail));
			tail->xor_with_next=(XORNode *)(((unsigned long long)newNode^(unsigned long long)head));
		}else{
			XORNode* prev = (XORNode *)((unsigned long long)tail->xor_with_next^(unsigned long long)head);
			std::cout<<"prev->data: "<<prev->data<<std::endl;
			XORNode* newNode = new XORNode(value, (XORNode *)(((unsigned long long)prev)^((unsigned long long)tail)));
			
			XORNode* pprev = (XORNode *)((unsigned long long)prev->xor_with_next^(unsigned long long)tail);
			std::cout<<"pprev->data: "<<pprev->data<<std::endl;
			prev->xor_with_next = (XORNode *)(((unsigned long long)pprev)^((unsigned long long)newNode));
			
			tail->xor_with_next=(XORNode *)(((unsigned long long)newNode)^((unsigned long long)head));
		}
    }

    // 查找节点
    XORNode* find(int target) {
    	if(head->xor_with_next==tail){
    		return NULL;
		}
    	
        XORNode* current = (XORNode *)(((unsigned long long)head->xor_with_next)^((unsigned long long)tail));
        
        XORNode* prev=head;
        while (current != tail) {
        	std::cout<<"current->data:"<<current->data<<std::endl;
            if (current->data == target) {
                return current;
            } else {
            	XORNode* temp=current;
            	
                current=(XORNode *)(((unsigned long long)current->xor_with_next)^((unsigned long long)prev));
                prev=temp;
            } 
        }
        return NULL;
    }

    // 释放内存
    ~XORLinkedList() {
        XORNode* next = NULL;
        while (head) {
            XORNode* temp = head;
           // head = head->xor_with_next;
            delete temp;
        }
    }
};

int main() {
    XORLinkedList list;
    list.append(1);
    
    list.append(2);
    
    list.append(3);list.append(4);
    
    XORNode* node = list.find(6);
    std::cout<<"search ending"<<std::endl;
    if (node) {
        std::cout << "Found node with value " << node->data << std::endl;
    } else {
        std::cout << "Node not found" << std::endl;
    }
    return 0;
}