http://www.reddit.com/r/dailyprogrammer/comments/1s061q/120313_challenge_143_easy_braille/

gistfile1.cpp

#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <iomanip>
#include <iostream>
#include <limits>
#include <string>
#include <vector>
#include <queue>
#include <unordered_map>

using namespace std;

void InitializeBrailleData(unordered_map<string, char>* rep) {
  rep->insert(make_pair("O.....", 'A'));
  rep->insert(make_pair("O.O...", 'B'));
  rep->insert(make_pair("OO....", 'C'));
  rep->insert(make_pair("OO.O..", 'D'));
  rep->insert(make_pair("O..O..", 'E'));
  rep->insert(make_pair("OOO...", 'F'));
  rep->insert(make_pair("OOOO..", 'G'));
  rep->insert(make_pair("O.OO..", 'H'));
  rep->insert(make_pair(".OO...", 'I'));
  rep->insert(make_pair(".OOO..", 'J'));
  rep->insert(make_pair("O...O.", 'K'));
  rep->insert(make_pair("O.O.O.", 'L'));
  rep->insert(make_pair("OO..O.", 'M'));
  rep->insert(make_pair("OO.OO.", 'N'));
  rep->insert(make_pair("O..OO.", 'O'));
  rep->insert(make_pair("OOO.O.", 'P'));
  rep->insert(make_pair("OOOOO.", 'Q'));
  rep->insert(make_pair("O.OOO.", 'R'));
  rep->insert(make_pair(".OO.O.", 'S'));
  rep->insert(make_pair(".OOOO.", 'T'));
  rep->insert(make_pair("O...OO", 'U'));
  rep->insert(make_pair("O.O.OO", 'V'));
  rep->insert(make_pair(".OOO.O", 'W'));
  rep->insert(make_pair("OO..OO", 'X'));
  rep->insert(make_pair("OO.OOO", 'Y'));
  rep->insert(make_pair("O..OOO", 'Z'));
};

void AddRepresentation(const string& line, vector<string>* representations) {
  for (int index = 0; index < line.length(); index += 3) {
    (*representations)[index / 3].push_back(line[index]);
    (*representations)[index / 3].push_back(line[index + 1]);

    assert((line[index + 2] == ' ') || (index + 2 == line.length()));
  }
}

int main() {
  unordered_map<string, char> braille_representation;
  InitializeBrailleData(&braille_representation);

  // Assume input is well formed.
  // This means we read three lines from standard input,
  // and each line's length is (3 * x - 1)
  string line1, line2, line3;
  getline(cin, line1);
  getline(cin, line2);
  getline(cin, line3);

  // Basic invariants
  assert(line1.length() == line2.length());
  assert(line2.length() == line3.length());
  assert((line1.length() + 1) % 3 == 0);

  // Get the input into our desired form
  vector<string> representations((line1.length() + 1) / 3);
  AddRepresentation(line1, &representations);
  AddRepresentation(line2, &representations);
  AddRepresentation(line3, &representations);

  for (const string& rep : representations) {
    cout << braille_representation[rep];
  }
  cout << endl;
}