破损的键盘（UVa 11988）

　　s[] 数组用来保存原有的字符序列

　　nex[] 数组记录打印的下标顺序

C++11 代码如下：

 1 #include<iostream>
 2 #include<cstring>
 3 using namespace std;
 4 #define maxn 100006
 5 char s[maxn];
 6 int nex[maxn], n;
 7 
 8 int main() {
 9     while (cin >> s + 1) {
10         int cur = 0, last = 0;
11         nex[0] = 0;
12         char ch;    
13         for (int i = 1; i <=strlen(s + 1); i++) {
14             ch = s[i];
15             if (ch == '[') cur = 0;
16             else if (ch == ']') cur = last;
17             else {
18                 nex[i] = nex[cur];
19                 nex[cur] = i;
20                 if (cur == last)last = i;
21                 cur = i;
22             }
23         }
24         for (int i = nex[0]; i != 0; i = nex[i])
25             cout << s[i];
26         cout << endl;
27     }
28     return 0;
29 }