Earth - Emily

lib/exercises.js

@@ -1,17 +1,55 @@
 // This method will return an array of arrays.
 // Each subarray will have strings which are anagrams of each other
-// Time Complexity: ?
-// Space Complexity: ?
+// Time Complexity: O(n+m)?
+// Space Complexity: O(n)
 function grouped_anagrams(strings) {
-  throw new Error("Method hasn't been implemented yet!");
+  let obj = {};
+
+  if (strings.length === 0) return [];
+
+  strings.forEach(string => {
+    // split each word into letters and sort alphabetially
+    let letters = string.split('').sort()
+
+    // if the letters exists, add string to key
+    // else add to obj
+    obj[letters] ? obj[letters].push(string) : obj[letters] = [string]
+    // create new array and add to results
+  });
+  // iterate through obj 
+  // return results 
+
+  const values = Object.values(obj)
+  // console.log("VALUES", values)
+  return values;
 }
 
 // This method will return the k most common elements
 // in the case of a tie it will select the first occuring element.
-// Time Complexity: ?
-// Space Complexity: ?
+// Time Complexity: O(nlog(n))?
+// Space Complexity: O(n)
 function top_k_frequent_elements(list, k) {
-  throw new Error("Method hasn't been implemented yet!");
+  let obj = {};
+  let results = [];
+
+  // if list is empty, retun empty
+  if (list.length === 0) return [];
+
+  // iterate through list, push elements into object
+  // if value doesn't exist, push new key or else +1
+  list.forEach(int => {
+    obj[int] = obj[int] ? obj[int] +1 : 1;
+  });
+  // o(n) + o(m) + o(nlogn)
+
+  // sorting inner array[1] from most frequent 
+  const sortedArray = Object.entries(obj).sort((a,b) => b[1] - a[1])
+
+  for(let i = 0; i < k; i++) {
+    results.push(parseInt(sortedArray[i]));
+  }
+
+  return results;
 }