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Dictionary.cpp
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Dictionary.cpp
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/*
* Dictionary.cpp
*
* Created on: Nov 11, 2015
* Author: Gessi
*/
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include "Dictionary.h"
using namespace std;
Dictionary::Dictionary(){
// constructing the dictionary
string fileName;
ifstream dictStream;
// read in the ditionary file name
do {
cout << "Enter dictionary file name: ";
cin >> fileName;
dictStream.open (fileName.c_str(), ios::in);
} while (!dictStream.good());
// keep trying until this works
string line;
// make sure the file has some stuff in it
if (!getline(dictStream, line)){
cerr << "Error: dictionary file is empty" << endl;
dictionary.clear();
return;
}
string word;
while (dictStream >> word) {
dictionary.push_back(word);
}
cout << "Dictionary size is " << dictionary.size()
<< endl << endl;
}
bool Dictionary::binarySearch(string word){
int dictStart = 0;
int dictEnd = dictionary.size() - 1;
// if the the word is not the same with the middle word
// in the dictionary, then execute the following codes
while (word.compare(dictionary.at
((dictStart + dictEnd)/2)) != 0) {
// Two cases where the binary search has reached the end
// and the word is not in the dictionary
if (dictStart == dictEnd || (dictStart == dictEnd - 1
&& word.compare(dictionary.at (dictEnd)) != 0)) {
return false;
// if there are portion of the dictionary to search
// through then reset the boundary where the target
// word might be
} else if (word.compare(dictionary.at
((dictStart + dictEnd)/2)) < 0) {
dictEnd = (dictStart + dictEnd)/2 - 1;
} else {
dictStart = (dictStart + dictEnd)/2 + 1;
}
}
// if the word is same with some word within the dictionary
// then return true
return true;
}
bool Dictionary::isPrefix(string word){
int dictStart = 0;
int dictEnd = dictionary.size() - 1;
// Similar idea as the binary search, but instead comparing
// the entire word, only compare the first few characters
while (word.compare((dictionary.at ((dictStart + dictEnd)/2))
.substr(0, word.length())) != 0) {
// Two scenarios where the given string is not a prefix
if (dictStart == dictEnd || (dictStart == dictEnd - 1 &&
word.compare((dictionary.at (dictEnd))
.substr(0, word.length())) != 0)) {
return false;
// Narrowing down next search's boundary
} else if (word.compare((dictionary.at
((dictStart + dictEnd)/2)).
substr(0, word.length())) < 0) {
dictEnd = (dictStart + dictEnd)/2 - 1;
} else {
dictStart = (dictStart + dictEnd)/2 + 1;
}
}
return true;
}