diff --git a/src/main/scala/wikipedia/WikipediaRanking.scala b/src/main/scala/wikipedia/WikipediaRanking.scala
index 1306b61..a035391 100644
--- a/src/main/scala/wikipedia/WikipediaRanking.scala
+++ b/src/main/scala/wikipedia/WikipediaRanking.scala
@@ -23,16 +23,22 @@ object WikipediaRanking extends WikipediaRankingInterface {
     "JavaScript", "Java", "PHP", "Python", "C#", "C++", "Ruby", "CSS",
     "Objective-C", "Perl", "Scala", "Haskell", "MATLAB", "Clojure", "Groovy")
 
-  val conf: SparkConf = ???
-  val sc: SparkContext = ???
+  val conf: SparkConf = new SparkConf().setMaster("local").setAppName("My wiki app")
+  val sc: SparkContext = new SparkContext(conf)
   // Hint: use a combination of `sc.parallelize`, `WikipediaData.lines` and `WikipediaData.parse`
-  val wikiRdd: RDD[WikipediaArticle] = ???
+  val wikiRdd: RDD[WikipediaArticle] = sc.parallelize(WikipediaData.lines).map(WikipediaData.parse);
 
   /** Returns the number of articles on which the language `lang` occurs.
    *  Hint1: consider using method `aggregate` on RDD[T].
    *  Hint2: consider using method `mentionsLanguage` on `WikipediaArticle`
    */
-  def occurrencesOfLang(lang: String, rdd: RDD[WikipediaArticle]): Int = ???
+  def occurrencesOfLang(lang: String, rdd: RDD[WikipediaArticle]): Int = {
+    def seqOp(acc : Int, art : WikipediaArticle): Int = {
+      val x = if(art.mentionsLanguage(lang)) 1 else 0
+      acc + x
+    }
+    rdd.aggregate(0 : Int)(seqOp, _ + _);
+  }
 
   /* (1) Use `occurrencesOfLang` to compute the ranking of the languages
    *     (`val langs`) by determining the number of Wikipedia articles that
@@ -42,12 +48,18 @@ object WikipediaRanking extends WikipediaRankingInterface {
    *   Note: this operation is long-running. It can potentially run for
    *   several seconds.
    */
-  def rankLangs(langs: List[String], rdd: RDD[WikipediaArticle]): List[(String, Int)] = ???
+  def rankLangs(langs: List[String], rdd: RDD[WikipediaArticle]): List[(String, Int)] = 
+    langs.map((lang : String) => (lang, occurrencesOfLang(lang, rdd))).sortBy(_._2).reverse;
 
   /* Compute an inverted index of the set of articles, mapping each language
    * to the Wikipedia pages in which it occurs.
    */
-  def makeIndex(langs: List[String], rdd: RDD[WikipediaArticle]): RDD[(String, Iterable[WikipediaArticle])] = ???
+  def makeIndex(langs: List[String], rdd: RDD[WikipediaArticle]): RDD[(String, Iterable[WikipediaArticle])] = {
+    (for{
+      art <- rdd
+      lang <- langs if art.mentionsLanguage(lang)
+    }yield{(lang, art)}).groupByKey
+  }
 
   /* (2) Compute the language ranking again, but now using the inverted index. Can you notice
    *     a performance improvement?
@@ -55,7 +67,8 @@ object WikipediaRanking extends WikipediaRankingInterface {
    *   Note: this operation is long-running. It can potentially run for
    *   several seconds.
    */
-  def rankLangsUsingIndex(index: RDD[(String, Iterable[WikipediaArticle])]): List[(String, Int)] = ???
+  def rankLangsUsingIndex(index: RDD[(String, Iterable[WikipediaArticle])]): List[(String, Int)] = 
+    index.mapValues(_.size).collect.sortBy(_._2).reverse.toList
 
   /* (3) Use `reduceByKey` so that the computation of the index and the ranking are combined.
    *     Can you notice an improvement in performance compared to measuring *both* the computation of the index
@@ -64,7 +77,13 @@ object WikipediaRanking extends WikipediaRankingInterface {
    *   Note: this operation is long-running. It can potentially run for
    *   several seconds.
    */
-  def rankLangsReduceByKey(langs: List[String], rdd: RDD[WikipediaArticle]): List[(String, Int)] = ???
+  def rankLangsReduceByKey(langs: List[String], rdd: RDD[WikipediaArticle]): List[(String, Int)] = {
+    val reducedRDD = (for{
+      art <- rdd
+      lang <- langs if art.mentionsLanguage(lang)
+    }yield{(lang, 1)}).reduceByKey(_ + _)
+    reducedRDD.collect.sortBy(_._2).reverse.toList
+  }
 
   def main(args: Array[String]): Unit = {