UVa 213 - Message Decoding

Accepted date: 2013-06-29
Ranking (as of 2013-06-29): 35 out of 870
Language: C++

/*
  UVa 213 - Message Decoding

  To build using Visucal Studio 2010:
    cl -EHsc UVa_213_Message_Decoding.cpp
*/

#include <cstdio>

int read_digits(int n)
{
  int d = 0, c;
  while (n--) {
    d <<= 1;
    while ((c = getchar()) == '\n')
      ;
    d += c - '0';
  }
  return d;
}

int main()
{
  char chars_map[1 + 3 + 7 + 15 + 31 + 63 + 127];
  const int chars_map_indices[] = {-1, 0, 1, 4, 11, 26, 57, 120};
    // chars_map_indices[i] is the index to chars_map[] for the key length of i
  const int terminaters[] = {0, 1, 3, 7, 15, 31, 63, 127};
    // terminaters[i] is the terminater for the key length of i
  while (true) {
    int c = getchar();
    if (c == EOF)
      break;
    else if (c == '\n')
      continue;
    // read a header
    char* p = chars_map;
    do
      *p++ = static_cast<char>(c);
    while ((c = getchar()) != '\n');
    int length;
    while (length = read_digits(3)) {
      char* q = &chars_map[chars_map_indices[length]];
      int i, t = terminaters[length];
      while ((i = read_digits(length)) != t)
        putchar(*(q + i));
    }
    putchar('\n');
  }
  return 0;
}