Description

Problem B

Broken Keyboard (a.k.a. Beiju Text)

You‘re typing a long text with a broken keyboard. Well it‘s not so badly broken. The only problem with the keyboard is that sometimes the "home" key or the "end" key gets automatically pressed (internally).

You‘re not aware of this issue, since you‘re focusing on the text and did not even turn on the monitor! After you finished typing, you can see a text on the screen (if you turn on the monitor).

In Chinese, we can call it Beiju. Your task is to find the Beiju text.

Input

There are several test cases. Each test case is a single line containing at least one and at most 100,000 letters, underscores and two special characters ‘[‘ and ‘]‘. ‘[‘ means the "Home" key is pressed internally,
and ‘]‘ means the "End" key is pressed internally. The input is terminated by end-of-file (EOF). The size of input file does not exceed 5MB.

Output

For each case, print the Beiju text on the screen.

Sample Input

This_is_a_[Beiju]_text
[[]][][]Happy_Birthday_to_Tsinghua_University

Output for the Sample Input

BeijuThis_is_a__text
Happy_Birthday_to_Tsinghua_University

Note: Please make sure to test your program with the gift I/O files before submitting!

看到网上一种指针的做法，感觉太厉害了，每次cur指向当前的点，然后把需要输出的字符插到cur的后面，当然这样后面的[]里面的东西会先输出来

根据是 ‘[‘  还是‘]‘改变  cur

具体自己好好想想

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define N 100005

char a[N];
int nest[N];
char ans[N];

int main()
{
   int i,j,len;
   while(gets(a))
   {
   	  int k,cur,last;
   	  k=cur=last=0;
   	  nest[0]=-1;
   	  for(i=0;a[i];i++)
	  {
	  	if(a[i]=='[')
			cur=0;
		else
		  if(a[i]==']')
			cur=last;
		else
		{
			k++;
			ans[k]=a[i];
			nest[k]=nest[cur];
			nest[cur]=k;
			cur=k;

			if(nest[k]==-1) last=k;
		}
	  }
	  int t=nest[0];
	  while(t!=-1)
	  {
	  	printf("%c",ans[t]);
	  	t=nest[t];
	  }
	  printf("\n");
   }
   return 0;
}