UVa 11988 Broken Keyboard

11988_broken_keyboard.cpp

#include <bits/stdc++.h>
using namespace std;

/* Solve the problem with double-linked list
 * We just need to record and update the next position to insert
 * the character.
 */
int main() {
  string line;
  while (getline(cin, line)) {
    list<char> ans;
    auto next_pos = ans.end();
    for (auto ch : line) {
      if (ch == '[') {
        next_pos = ans.begin();
      } else if (ch == ']') {
        next_pos = ans.end();
      } else {
        next_pos = next(ans.insert(next_pos, ch));
      }
    }
    cout << string(ans.begin(), ans.end()) << endl;
  }

  return 0;
}