word-freq-list.cc

/*
   Word list by frequency
   Written by Igor N. Dultsev

   Tested to compile by Visual C++ Compiler version 19.10.24903.0 (x86) with no additional keys
   For compilation with g++, use the following command: g++ -std=c++14 word-freq-list.cc
 */
 
#include <iostream>
#include <map>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;

extern "C" int getchar();


// written as is to increase readability
bool isEnglishLetter(char c)
{
	if (c >= 'A' && c <= 'Z')
		return true;
	if (c >= 'a' && c <= 'z')
		return true;
	return false;
}

// returns true if EOF is reached, otherwise returns false
bool getNextWord(string &result)
{
	char c;
	while (true)
	{
		c = (char) getchar();
		if (c == EOF)
			return true;
		if (isEnglishLetter(c))
			result += c;
		else
			return false;
	}
	return false;
}

// get all words in the map
 void getWordMap(vector<pair<string, int>> & result) {
	map<string, int> dict;

	bool eof = false;
	while (!eof)
	{
		string s;
		eof = getNextWord(s);
		if (s.length() == 0)
			continue; // ignore empty words

		if (dict.count(s) > 0)
			dict[s]++;
		else
			dict[s] = 1;
	}
	copy(dict.begin(), dict.end(), back_inserter(result));
}

int main()
{

	vector<pair<string, int>> plist;
	getWordMap(plist);

	auto cmp = [](auto &f, auto &s) { return f.second == s.second ? f.first < s.first : f.second > s.second; };
	std::sort(plist.begin(), plist.end(), cmp);

	for (auto it = plist.begin(); it != plist.end(); it++)
		cout << it->second << ' ' << it->first << endl;

	return 0;
}