add Space Complexity examples

Author: dmakwt

big-o/double.js

@@ -0,0 +1,11 @@
+// Space Complexity: O(n)space!
+
+function double(arr){
+    let newArr = [];
+
+    for(let i = 0; i < arr.length; i++){
+        newArr.push(2 * arr[i]);
+    }
+
+    return newArr;
+}

big-o/sum.js

@@ -0,0 +1,11 @@
+// Space Complexity: O(1)space!
+
+function sum(arr){
+    let total = 0;
+
+    for(let i = 0 ; i < arr.length; i++){
+        total += arr[i];
+    }
+
+    return total;
+}