【POJ1208】The Blocks Problem

来源：The Blocks Problem

推导：（略）

设计：

　　f(i): 把叠在木块i上的其他木块放回初始位置.

　　m(i,j): 把i及其以上的木块全叠到包含j的上方.

　　move a onto b => f(a),f(b),m(a,b)

　　move a over b => f(a),m(a,b)

　　pile a onto b   => f(b),m(a,b)

　　pile a over b  => m(a,b)

代码：

#include <iostream>
using namespace std;

#define N 24

//块
struct Node{
    int No; //编号
    struct Node *next;
};

struct Node *station[N];//原始的块位置
int place[N];//当前各块所在的位置

struct Node *Find(int i,bool setNULL)
{
    struct Node *p,*q;
    int j = place[i];
    if(station[j]->No == i)
    {
        p=station[j];
        if(setNULL)
            station[j] = NULL;
        return p;
    }
    else
    {
        q=station[j];
        p=q->next;
        while(p->No!=i)
        {
            q=p;
            p=q->next;
        }
        if(setNULL)
            q->next=NULL;
        return p;
    }
}

void F(int i)
{
    struct Node *p;
    p=Find(i,false);

    if(p->next==NULL)
        return;

    int j;
    while(p->next!=NULL)
    {
        j = p->next->No;
        station[j] = p->next;
        place[j] = j;
        p->next=NULL;
        p=station[j];
    }
}

void M(int i,int j)
{
    if( i==j || place[i]==place[j] )
        return;

    struct Node *p,*q;
    p=Find(i,true);
    q=Find(j,false);

    while(q->next!=NULL)
        q=q->next;

    q->next = p;

    while(p!=NULL)
    {
        place[p->No]=place[q->No];
        p=p->next;
    }

}

void MoveAOntoB(int i,int j)
{
    F(i);
    F(j);
    M(i,j);
}

void MoveAOverB(int i,int j)
{
    F(i);
    M(i,j);
}

void PileAOntoB(int i,int j)
{
    F(j);
    M(i,j);
}

void PileAOverB(int i,int j)
{
    M(i,j);
}

void Init()
{
    for( int i=0;i<N;i++ )
    {
        place[i] = i;
        station[i] = (struct Node *)malloc(sizeof(struct Node));
        station[i]->No = i;
        station[i]->next = NULL;
    }

}

int main()
{
    int n;
    char ch1[5],ch2[5];
    int a,b;    
    struct Node *p;
    cin >> n;
    Init();
    while(cin >> ch1 && strcmp(ch1,"quit")!=0 )
    {
        cin >> a;
        cin >> ch2;
        cin >> b;
        if( strcmp(ch1,"move")==0 )
        {
            if( strcmp(ch2,"onto")==0 )
                MoveAOntoB(a,b);
            else
                MoveAOverB(a,b);
        }
        else
        {
            if( strcmp(ch2,"onto")==0 )
                PileAOntoB(a,b);
            else
                PileAOverB(a,b);
        }
    }

    for( int i=0;i<n;i++ )
    {
        cout<<i<<": ";
        p = station[i];
        while(p!=NULL)
        {
            cout<<p->No<<" ";
            p=p->next;
        }
        cout << endl;
    }
    
    return 1;
}