Merge pull request #92 from front-studium/sgoldenbird

`week22` 풀었습니다.

Author: sgoldenbird

sgoldenbird/level_0/배열_두_배_만들기.js

@@ -0,0 +1,3 @@
+function solution(numbers) {
+  return numbers.map((num) => num * 2);
+}

sgoldenbird/level_0/중복된_숫자_개수.js

@@ -0,0 +1,11 @@
+function solution(array, n) {
+  let count = 0;
+
+  for (let el of array) {
+    if (el === n) count++;
+  }
+
+  return count;
+}
+
+// filter/reduce로 푸는 것도 가능