/*
 * A tiny T9 predictive-text demo.
 *
 * Students should fill in AddPrefixesToPredictions and PrintPredictions.
 */

#include <iostream>
#include <map>
#include <string>
#include <vector>

using std::cout;
using std::endl;
using std::map;
using std::string;
using std::vector;

const map<char, char> letters_to_keys = {
    {'a', '2'}, {'b', '2'}, {'c', '2'},
    {'d', '3'}, {'e', '3'}, {'f', '3'},
    {'g', '4'}, {'h', '4'}, {'i', '4'},
    {'j', '5'}, {'k', '5'}, {'l', '5'},
    {'m', '6'}, {'n', '6'}, {'o', '6'},
    {'p', '7'}, {'q', '7'}, {'r', '7'}, {'s', '7'},
    {'t', '8'}, {'u', '8'}, {'v', '8'},
    {'w', '9'}, {'x', '9'}, {'y', '9'}, {'z', '9'},
};

map<string, vector<string>> predictions;  // global prediction map

void AddPrefixesToPredictions(const string& word) {
  (void) word;

  // TODO: Build up the T9 key prefix for this word one letter at a time.
  // For each prefix, add word to predictions[prefix].
}

void PrintPredictions() {
  // TODO: Loop over every pair in predictions.
  // Print the key prefix, then every predicted word for that prefix.
}

void BuildPredictions(const vector<string>& words) {
  predictions.clear();

  for (const string& word : words) {
    AddPrefixesToPredictions(word);
  }
}

int main() {
  const vector<string> words = {
      "bat", "cat", "catalog", "dog", "door", "fish", "hello", "help",
      "home", "good", "gone", "world",
  };

  BuildPredictions(words);
  PrintPredictions();

  return 0;
}