一、問題概述

廣義表是非線性的數據結構，是由若干個元素組合而成的，廣義表中可以有子表，類似這樣的：

我們以C=(a,b,(c,d))為例，將它定義為這樣的數據結構：

我們會給定字符串的形式，如：char * str = "(a,b,(c,d))";???? 然后將它轉化為如上的數據結構。

二、解決辦法

（1）將符號'('看作是頭節點，然后將是數值的部分鏈入當前位置的下一個位置；

（2）當遇到SUB時，就鏈入它的_sublink（連接子表的指針），此時可用遞歸（子表相當于是表的子問題）；

（3）直到str為空時，廣義表的數據結構創建完成。

三、實現代碼

//GeneralizedList.h

#pragma once 
#include<iostream>
using namespace std;
#include<assert.h>enum Type
{HEAD,VALUE,SUB,
};struct GeneralizeListNode
{Type _type;GeneralizeListNode* _next;union{char _value;GeneralizeListNode* _sublink;};GeneralizeListNode(Type type,char value = 0):_next(NULL),_type(type),_value(value){if(type == VALUE){_value = value;}if(type == SUB){_sublink = NULL;}}
};class GeneralizeList
{typedef GeneralizeListNode Node;
public:GeneralizeList():_head(NULL){}//構造函數GeneralizeList(const char* str){_head = Create(str);}//拷貝構造函數GeneralizeList(const GeneralizeList& g){_head = _Copy(g._head);}//賦值運算符重載（1）//GeneralizeList& operator=(const GeneralizeList& g)//{//	if(this != &g)//	{//		Node* tmp = _Copy(g._head);//		delete _head;//		_head = tmp;//	}//	return *this;//}//賦值運算符重載（2）GeneralizeList& operator=(const GeneralizeList& g){if(_head != g._head){GeneralizeList tmp(g);swap(_head,tmp._head);}return *this;}~GeneralizeList(){if(_head){_Destroy(_head);_head = NULL;}}void Print(){_Print(_head);cout<<endl;}public:Node* Create(const char*& str)            //創建表{assert(*str == '(');Node* head = new Node(HEAD);++str;Node* tail = head;while(*str){if((*str >= '0' && *str <= '9')||(*str >= 'a' && *str <= 'z')||(*str >= 'A' && *str <= 'Z')){tail->_next = new Node(VALUE,*str);tail = tail->_next;++str;}else if(*str == '('){tail->_next = new Node(SUB);tail = tail->_next;tail->_sublink = Create(str);++str;}else if(*str == ')'){++str;return head;}else{++str;}}return head;}void _Print(Node* head){assert(head);Node* cur = head;while(cur){if(cur->_type == HEAD){cout<<"(";}else if(cur->_type == VALUE){cout<<cur->_value;if(cur->_next != NULL){cout<<",";}}else if(cur->_type == SUB){_Print(cur->_sublink);if(cur->_next != NULL){cout<<",";}}else{assert(false);}cur = cur->_next;}cout<<")";}Node* _Copy(Node* head){Node* cur = head;Node* newHead = new Node(HEAD);Node* newTail = newHead;while(cur){if(cur->_type == HEAD){cur = cur->_next;}else if(cur->_type == VALUE){newTail->_next = new Node(VALUE,cur->_value);newTail = newTail->_next;cur = cur->_next;}else if(cur->_type == SUB){newTail->_next = new Node(SUB);newTail = newTail->_next;newTail->_sublink = _Copy(cur->_sublink);cur = cur->_next;}else{assert(false);}}return newHead;}void _Destroy(Node* head)       //銷毀表{Node* cur = head;while(cur){if(cur->_type == HEAD || cur->_type == VALUE){Node* del = cur;cur = cur->_next;delete del;}else if(cur->_type == SUB){Node* del = cur;cur = cur->_next;_Destroy(del->_sublink);delete del;}else{assert(false);}}}size_t Size(){return _Size(_head);}size_t _Size(Node* head)              //元素個數{assert(head);size_t count = 0;Node* cur = head;while(cur){if(cur->_type == VALUE){++count;}else if(cur->_type == SUB){count += _Size(cur->_sublink);}cur = cur->_next;}return count;}size_t Depth(){return _Depth(_head);}size_t _Depth(Node* head)        //表的深度{Node* cur = head;size_t MaxDepth = 1;while(cur){if(cur->_type == SUB){size_t Depth = _Depth(cur->_sublink);if(Depth+1 > MaxDepth){MaxDepth = Depth+1;}}cur = cur->_next;}return MaxDepth;}
protected:Node* _head;
};void FunTest()
{char* str = "(a,b,(c,d),(e,(f),g))";GeneralizeList g1(str);g1.Print();GeneralizeList g2(g1);g2.Print();GeneralizeList g3;g3 = g1;g3.Print();cout<<g3.Size()<<endl;cout<<g3.Depth()<<endl;
}

//GeneralizedList.cpp

#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
#include"GeneralizedList.h"
int main()
{FunTest();return 0;
}

四、運行結果