POJ 2003 Hire and Fire (多重链表 树结构 好题)

• [existing member] hires [new member]
  
• fire [existing member]
  
• print

• Each line in the textual representation of the tree will contain exactly one name.
  
• The first line will contain the CEO‘s name, starting in column 1.
  
• The entire tree, or any sub-tree, having the form
  
  will be represented in textual form as:
  

#include <cstdio>
#include <string>
#include <iostream>
#include <list>
#include <map>
using namespace std;

struct Tree
{
    string name;            //结点名字
    Tree *fa;               //结点父指针
    list <Tree *> son;      //结点儿子指针链表
    Tree()
    {
        fa == NULL;
    }
};

map <string, Tree *> mp;    //结点与其树指针的键值对

void Print(int dep, Tree *now)  //先序递归输出
{
    if(!now)
        return;
    for(int i = 0; i < dep; i++)
        printf("+");
    cout << now -> name << endl;
    for(list <Tree *> :: iterator it = now -> son.begin(); it != now -> son.end(); it++)
        Print(dep + 1, *it);
    return;
}

void Fire(string del)   
{   
    Tree *s = mp[del];      //得到该点的树指针      
    while((int)s -> son.size() != 0)    //遍历最左位置
    {
        //下面三步相当于把当前结点的儿子上移
        s -> name = s -> son.front() -> name;  
        mp[s -> name] = s;
        s = s -> son.front();
    }
    //此时的s到达最左的叶子处，可以删除
    mp.erase(del);              //释放以del为根的子树
    s -> fa -> son.remove(s);   //将其从其父亲的儿子指针链表中删除
    delete s;                   //删除s
}

void Hire(string fir, string sec)
{
    Tree *f = mp[fir];          //得到父指针
    Tree *s = new Tree();       //新建一个指针域
    s -> fa = f;                //将其指向父指针
    s -> name = sec;            //命名
    mp[sec] = s;                //建立其与树指针的键值关系
    f -> son.push_back(s);      //将其加入父亲的儿子指针链表中
    return;
}

int main()
{
    string rt, fir, sec;
    cin >> rt;
    Tree *root = new Tree();
    mp[rt] = root;
    root -> name = rt;
    while(cin >> fir)
    {
        if(fir == "print")
        {
            Print(0, root);
            printf("------------------------------------------------------------\n");
        }
        else if(fir == "fire")
        {
            cin >> sec;
            Fire(sec);
        }
        else
        {
            string tmp;
            cin >> tmp >> sec;
            Hire(fir, sec);
        }
    }
}