习题3.4 & 3.5： 求两链表的交集和并集

#include<stdio.h>
#include<stdlib.h>
struct Node;
typedef struct Node *PtrToNode;
typedef PtrToNode List;
typedef PtrToNode Position;

struct Node{
    ElementType Ele;
    PtrToNode Next;
};

Position
First( List L )
{
    return L->Next;
}
Position
Next( List L, Position p )
{
    return  p->Next;
}

List
CreateAndMakeEmpty( List L )
{
    L = malloc( sizeof( struct Node ) );
    if( L == NULL )
        Error("out of space ");
    L->Next = NULL;
    return L;
}

void
Insert( Position p, ElementType X )
{
    Position TmpCell;
    TmpCell = malloc( sizeof( struct Node ) );
    if( TmpCell == NULL )
        Error("out of space ");
    TmpCell->Ele = X;
    TmpCell->Next = p->Next;
    p->Next = TmpCell;
}
List
FindSimilar( List L1, List L2 )
{
   Position L1Pos,L2Pos,LresPos;
   List Lres;
   CreateAndMakeEmpty( Lres ); 
   LresPos = Lres;
   L1Pos = First(L1);
   L2Pos = First(L2);
   while( L1Pos != NULL && L2Pos != NULL )
   {
        if( L1Pos->Ele > L2Pos->Ele )
            next( L2, L2Pos );
        else if( L1Pos->Ele < L2Pos->Ele )
            next( L1, L1Pos )
        else
        {
            Insert( LresPos, L1Pos->Ele );
            LresPos = LresPos->Next;
            L1Pos = next( L1, L1Pos );
            L2Pos = next( L2, L2Pos );
        }
   }
}
void
PrintList( List Lres )
{
    Position p;
    p = First( Lres );
    while( p != NULL )
    {
        printf("%?",p->Ele);
        p = p->Next;
    }
}

List
GetUnion( List L1, List L2 )
{
    ElementType InsertEle;
    List Lres;
    Position L1Pos,L2Pos,LresPos;
    L1Pos = First( L1 );
    L2Pos = First( L2 );
    Lres = CreateAndMakeEmpty( Lres );
    LresPos = Lres;
    while( L1Pos != NULL && L2Pos != NULL )
    {
        if( L1Pos->Ele < L2Pos->Ele )
        {
            InsertEle = L1Pos->Ele;
            L1Pos = next( L1, L1pos );
        }
        else if( L1Pos->Ele > L2Pos->Ele )
        {
            InsertEle = L2Pos->Ele;
            L2Pos = next( L2, L2Pos );
        }
        else
        {
            InsertEle = L1Pos->Ele;
            L1Pos = next( L1, L1Pos ); L2Pos = next( L2, L2Pos );
        }
        Insert( LresPos, InsertEle );
        LresPos = next( Lres, LresPos );
    }
    while( L1Pos != NULL )
    {
        InsertEle = L1Pos->Ele;
        Insert( LresPos, InsertEle );
        LresPos = next( Lres, LresPos );
        L1Pos = next( L1Pos );
    }
    while( L2Pos != NULL )
    {
        InsertEle = L2Pos->Ele;
        Insert( LresPos, InsertEle );
        LresPos = next( Lres, LresPos );
        L2Pos = next( L2, L2Pos );
    }
    printList();
}