Uva 11988 （Broken Keyboard）悲劇文本

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

Sample Input

This_is_a_[Beiju]_text

[[]][][]Happy_Birthday_to_Tsinghua_University

Sample Output

BeijuThis_is_a__text

Happy_Birthday_to_Tsinghua_University

 

 1 /*Uva11988
 2 運用鏈表一個next[i]存儲着下一個s[i]的位置，next[0]爲表頭，指向一開始須要輸出的s[i]的值。
 3 */
 4 #include<iostream>
 5 #include<cstdio>
 6 #include<cstring>
 7 const int maxn = 100000 + 5;
 8 char s[maxn];
 9 int next[maxn];
10 int main()
11 {
12     while (scanf_s("%s", s + 1,maxn) == 1)
13     {
14         int n = strlen(s + 1);
15         next[0] = 0;
16         int cur = 0, last = 0;
17         for (int i = 1; i <= n; i++)
18         {
19             char ch = s[i];
20             if (ch == '[')cur = 0;//更新next[0]的指向
21             else if (ch == ']')cur = last;//使next[cur]指向【前的位置；即開始的鏈表被移動到了後方，
22                                           //【】內的內容被放在了前面
23             else
24             {
25                 /*此處相似於鏈表的添加，不斷更新尾部地址*/
26                 next[i] = next[cur];//next[cur]存儲的是下一個指向的地址
27                                     //如果普通狀況，就將待打印字符（當前的最後一個字符）指向0
28                                     //若是遇到【】狀況，當遇到了【，
29                                     //那麼next[i]存儲next[0]的值也就是next[i]指向了普通狀況的第一個字符，
30                                     //同時更新next[0]的值指向【的下一個位置。
31                 next[cur] = i;//前一個位置的next存儲着下一個next的地址即s[i]中的i
32                 if (cur == last)last = i;
33                 cur = i;
34             }
35         }
36         for (int i = next[0]; i != 0; i = next[i])
37             printf("%c", s[i]);
38         printf("\n");
39     }
40     return 0;
41 }