Given the name of a file that contains a list of words and a single word, print the words from the file that are anagrams of the given single word.

anagram.cpp

#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;




/// Returns true if word1 is an anagram of word2.
bool is_anagram(const string& word1, const string& word2)
{
  string sorted_word1 = word1;
  sort(sorted_word1.begin(), sorted_word1.end());

  string sorted_word2 = word2;
  sort(sorted_word2.begin(), sorted_word2.end());

  return (sorted_word1 == sorted_word2);
}




/// Return a list of indices of words that are anagrams of word
vector<size_t> get_anagrams(const vector<string>& words, const string& word)
{
  vector<size_t> result;

  size_t i = 0;
  vector<string>::const_iterator iter = words.begin();
  for (; iter != words.end(); ++iter, ++i)
  {
    if (is_anagram(*iter, word))
    {
      result.push_back(i);
    }
  }

  return result;
}




/// Given the name of a file that contains a list of words and a single word,
/// print the words from the file that are anagrams of the given single word.
int main(int argc, char* argv[])
{
  if (argc != 3)
  {
    cerr << "expected anagram word_list_filename target_word" << endl;
    return -1;
  }

  string filename = argv[1];
  string target_word = argv[2];

  ifstream list_file(filename.c_str(), std::ifstream::in);

  vector<string> word_vector;
  string word;
  while(getline(list_file, word))
  {
    word_vector.push_back(word);
  }

  vector<size_t> indices = get_anagrams(word_vector, target_word);

  for (vector<size_t>::iterator i = indices.begin(); i != indices.end(); ++i)
  {
    string anagram = word_vector[*i];
    if (anagram != target_word)
    {
      cout << anagram << endl;
    }
  }

  return 0;
}