diff --git a/03week/towersOfHanoi.js b/03week/towersOfHanoi.js
index 3cf6df049..14d8893a5 100644
--- a/03week/towersOfHanoi.js
+++ b/03week/towersOfHanoi.js
@@ -7,39 +7,103 @@ const rl = readline.createInterface({
   output: process.stdout
 });
 
+// the 'towers', as an object which contains three arrays:
 let stacks = {
   a: [4, 3, 2, 1],
   b: [],
   c: []
 };
 
-function printStacks() {
+// a couple variables to count number of moves per game as well as best score:
+let moveCount = 0;
+let bestCount = 0;
+
+// reset function to reset when a game is complete:
+let reset = () => {
+  stacks = {
+    a: [4, 3, 2, 1],
+    b: [],
+    c: []
+  };
+  moveCount = 0;
+}
+
+let printStacks = () => {
   console.log("a: " + stacks.a);
   console.log("b: " + stacks.b);
   console.log("c: " + stacks.c);
 }
 
-function movePiece() {
-  // Your code here
-
+// validity check function with a switch statement to explicitly define valid inputs:
+let isValid = ( startStack, endStack ) => {
+  switch( startStack ) {
+    case 'a':
+    case 'b':
+    case 'c':
+      break;
+    default:
+      return false;
+  }
+  switch( endStack ) {
+    case 'a':
+    case 'b':
+    case 'c':
+      return true;
+    default:
+      return false;
+  }
 }
 
-function isLegal() {
-  // Your code here
-
+// function to check for legality of attempted move:
+let isLegal = (startStack, endStack) => {
+  // define a couple variables to represent the final item in each selected stack for comparsion purposes:
+  let lastStart = stacks[startStack].length - 1;
+  let lastEnd = stacks[endStack].length - 1;
+  // if the final item in the chosen startStack is less than the final item in the chosen endStack, OR if the chosen endStack is empty (undefined), return true (move is valid):
+  if( (stacks[startStack][lastStart] < stacks[endStack][lastEnd]) || stacks[endStack][lastEnd] == undefined ) {
+    return true;
+  }
+  else return false;
 }
 
-function checkForWin() {
-  // Your code here
-
+// check for win: if the final tower is full, returns true:
+let checkForWin = () => {
+  if( stacks.c.length == 4 ) {
+    return true;
+  }
+  else return false;
 }
 
-function towersOfHanoi(startStack, endStack) {
-  // Your code here
-
+let towersOfHanoi = (startStack, endStack) => {
+  // check if the inputs are valid:
+  if(!isValid(startStack, endStack)) {
+    console.log('Try again, choose either "a", "b", or "c"!');
+  }
+  // then check if the move is legal:
+  else if( !isLegal(startStack, endStack) ) {
+    console.log('Try again with a valid move!');
+  }
+  // if it's valid and legal, move the piece:
+  else {
+    // pop the final element in the array defined by startStack, and push it to the array defined by endStack:
+    stacks[endStack].push( stacks[startStack].pop() );
+    // add one to the number of moves which have occured:
+    moveCount++
+  }
+  // see if checkForWin() evaluates as true:
+  if( checkForWin() ) {
+    // if game is won in less moves than the best score (or if it's the first score), update best score:
+    if( (moveCount < bestCount) || (bestCount == 0) ) {
+      bestCount = moveCount;
+    }
+    // console.log the win, display how many moves it took to win and the player's best score:
+    console.log(`You won in ${moveCount} moves! Your best was ${bestCount} moves!`);
+    // reset the board:
+    reset();
+  }
 }
 
-function getPrompt() {
+let getPrompt = () => {
   printStacks();
   rl.question('start stack: ', (startStack) => {
     rl.question('end stack: ', (endStack) => {
@@ -80,7 +144,7 @@ if (typeof describe === 'function') {
   });
   describe('#checkForWin()', () => {
     it('should detect a win', () => {
-      stacks = { a: [], b: [4, 3, 2, 1], c: [] };
+      stacks = { a: [], b: [], c: [4, 3, 2, 1] };
       assert.equal(checkForWin(), true);
       stacks = { a: [1], b: [4, 3, 2], c: [] };
       assert.equal(checkForWin(), false);