UVA - 11988：Broken Keyboard (a.k.a. Beiju Text)

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

来源：UVA
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参考资料：《算法竞赛入门经典》P143
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题目

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.

输入

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).

输出

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

输入样例

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

样例输出

BeijuThis_is_a__text
Happy_Birthday_to_Tsinghua_University

参考代码

#include
#include
const int maxn=100000+5;
int last,cur,next[maxn];
char s[maxn];
int main()
{
	while(scanf("%s",s+1)==1)
	{
		int n=strlen(s+1);
		last=cur=0;
		next[0]=0;
		
		for(int i=1;i<=n;i++)
		{
			char ch=s[i];
			if(ch=='[')cur=0;
			else if(ch==']')cur=last;
			else {
				next[i]=next[cur];
				next[cur]=i;
				if(cur==last) last=i;
				cur=i;
			}
		}
		for(int i=next[0];i!=0;i=next[i])
			printf("%c",s[i]);
		printf("\n");
	}
	return 0;
}