UVa 271 - Simply Syntax

Accepted date: 2012-09-08
Ranking (as of 2013-02-02): 76
Language: C++

/*
  UVa 271 - Simply Syntax

  To build using Visucal Studio 2008:
    cl -EHsc -O2 simply_syntax.cpp
*/

#include <cstdio>
#include <cstring>

int get_sentence(const char* s, int i, int length)
{
  if (i >= length)
    return -1;
  char c = s[i];
  if (c == 'N') {
    int j = get_sentence(s, i + 1, length);
    return (j == -1) ? j : j + 1;
  }
  else if (c == 'C' || c == 'D' || c == 'E' || c == 'I') {
    int j = get_sentence(s, i + 1, length);
    if (j == -1)
      return -1;
    int k = get_sentence(s, i + j + 1, length);
    return (k == -1) ? -1 : j + k + 1;
  }
  else
    return 1;
}

int main()
{
  const int nr_chars_max = 256;
  char s[nr_chars_max + 1];
  while (gets(s)) {
    int length = strlen(s);
    printf("%s\n", ((get_sentence(s, 0, length) == length) ? "YES" : "NO"));
  }
  return 0;
}