Working!

src/wordchain.cpp

@@ -5,7 +5,7 @@
 #include <string>
 #include <unordered_set>
 
-const string ALPHABET = "abcdefghijklmnopqrstuvwxyz";
+const std::string ALPHABET = "abcdefghijklmnopqrstuvwxyz";
 
 const char *const FORMAT_UNDERSCORE = "\033[4m";
 const char *const END_FORMATTING = "\033[0m";
@@ -57,19 +57,80 @@ std::unordered_set<std::string> readDictionary() {
     return set;
 }
 
+std::stack<std::string>
+wordChain(std::string &w1, std::string &w2,
+          const std::unordered_set<std::string> &dictionary) {
+    std::unordered_set<std::string> visited;
+    std::queue<std::stack<std::string>> queue;
+    {
+        std::stack<std::string> first;
+        first.push(w1);
+        queue.push(first);
+    }
+    visited.insert(w1);
+
+    while (!queue.empty()) {
+        std::stack<std::string> front = queue.front();
+        queue.pop();
+        std::string latestWord = front.top();
+        if (latestWord == w2)
+            return front;
+        for (int i = 0; i < latestWord.size(); i++) {
+            for (char c : ALPHABET) {
+                std::string nextWord = latestWord;
+                nextWord[i] = c;
+                bool isVisited = visited.find(nextWord) != visited.end();
+                if (isVisited)
+                    continue;
+                bool isValidWord = dictionary.find(nextWord) != dictionary.end();
+                if (!isValidWord)
+                    continue;
+                std::stack<std::string> nextStack = front;
+                nextStack.push(nextWord);
+                queue.push(nextStack);
+                visited.insert(nextWord);
+            }
+        }
+    }
+
+    return std::stack<std::string>();
+}
+
 int main() {
     std::cout << "Welcome to TDDD86 Word Chain.\n"
               << "If you give me two English words, I will transform the\n"
               << "first into the second by changing one letter at a time.\n\n"
-              <<"Please type two words: ";
+              << "Please type two words: ";
     std::flush(std::cout);
 
     std::unordered_set<std::string> dictionary = readDictionary();
+
     std::string userInput = input(nullptr);
     size_t wordSep = userInput.find(' ');
     std::string wordOne = userInput.substr(0, wordSep);
     std::string wordTwo = userInput.substr(wordSep + 1);
-    std::cout << "Chain from " << wordTwo << " to " << wordOne << std::endl;
+
+    // std::string wordOne = "lead", wordTwo = "gold";
+    std::cout << "Chain from " << wordTwo << " to " << wordOne << ':'
+              << std::endl;
+    std::stack<std::string> resolutionWords =
+        wordChain(wordOne, wordTwo, dictionary);
+
+    bool isFirst = true;
+    if (!resolutionWords.empty()) {
+        do {
+            std::string resolutionWord = resolutionWords.top();
+            resolutionWords.pop();
+            if (isFirst) {
+                isFirst = false;
+            } else {
+                std::cout << ", ";
+            }
+            std::cout << resolutionWord;
+        } while (!resolutionWords.empty());
+    } else
+        std::cout << "Couldn't find any resolution :(";
+    std::cout << std::endl;
 
     std::cout << "Have a nice day!" << std::endl;
     return 0;