HDU 4041 Eliminate Witches! --模拟

题意： 给一个字符串，表示一颗树，要求你把它整理出来，节点从1开始编号，还要输出树边。

解法： 模拟即可。因为由括号，所以可以递归地求，用map存对应关系，np存ind->name的映射，每进入一层括号，使father = now， 遇到右括号')'，则father = fa[father]，用vector存每个节点的子节点，然后最后dfs输出即可。

代码：

#include <iostream>

#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <cmath>

#include <algorithm>

#include <string>

#include <vector>

#include <map>

using namespace std;

#define N 50017



string ss,tmp,S;

string np[N];

map<string,int> mp;

int fa[N],father,ind;

vector<int> G[N];



void Go(int u,int v,int father)

{

    tmp = "";

    int j;

    for(int i=u;i<v;i++)

    {

        if(ss[i] >= 'a' && ss[i] <= 'z')

            tmp += ss[i];

        else if(ss[i] == '(' || ss[i] == ',' || ss[i] == ')')

        {

            if(tmp == "") continue;

            mp[tmp] = ++ind;

            np[ind] = tmp;

            tmp = "";

            fa[ind] = father;

            G[father].push_back(ind);

            if(ss[i] == '(')

            {

                int cnt = 1;

                for(j=i+1;j<v;j++)

                {

                    if(ss[j] == '(') cnt++;

                    else if(ss[j] == ')')

                    {

                        cnt--;

                        if(cnt == 0) break;

                    }

                }

                Go(i+1,j,ind);

                i = j;

            }

            else if(ss[i] == ')')

                father = fa[father];

        }

    }

    if(tmp != "")

    {

        mp[tmp] = ++ind;

        np[ind] = tmp;

        tmp = "";

        fa[ind] = father;

        G[father].push_back(ind);

    }

}



void dfs(int u)

{

    for(int i=0;i<G[u].size();i++)

    {

        int v = G[u][i];

        printf("%d %d\n",u,v);

        dfs(v);

        printf("%d %d\n",v,u);

    }

}



int main()

{

    int t,i,j,len;

    scanf("%d",&t);

    while(t--)

    {

        mp.clear();

        for(i=0;i<=50000;i++)

            G[i].clear();

        cin>>ss;

        len = ss.length();

        father = 0;

        ind = 0;

        Go(0,len,0);

        printf("%d\n",ind);

        for(i=1;i<=ind;i++)

            cout<<np[i]<<endl;

        dfs(1);

        puts("");

    }

    return 0;

}

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