02_advanced/uebungen/u05_sum-rekursiv/index.html

@@ -1,10 +1,11 @@
-<!DOCTYPE html>
+<!doctype html>
 <html lang="de">
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Übung 5: Summe einer Zahlenreihe rekursiv berechnen</title>
     <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.8/dist/css/bootstrap.min.css" rel="stylesheet" />
+    <script src="https://cdn.jsdelivr.net/npm/lodash@4.18.1/lodash.min.js"></script>
   </head>
   <body>
     <main>
@@ -28,12 +29,33 @@
     <script>
       'use strict';
 
-      const sumRecursive = (n) => {};
+      const sumRecursive = (n) => {
+        // Basisfall
+        if (n === 0) {
+          return 0;
+        }
+
+        return n + sumRecursive(n - 1); // Rekursion
+      };
+
+      const sumReduce = (n) => {
+        const numbers = _.range(1, n + 1); // => [1,2,3,4,5]
+        return numbers.reduce((sum, n) => sum + n, 0);
+      };
 
       // Test Cases
+
+      console.log(_.range(5)); // => [0,1,2,3,4]
+      console.log(_.range(2, 5)); // => [2,3,4]
+      console.log(_.range(2, 10, 2)); // => [2,4,6,8]
+
       console.log(sumRecursive(5)); // => 15 (5 + 4 + 3 + 2 + 1)
       console.log(sumRecursive(10)); // => 55 (10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1)
       console.log(sumRecursive(0)); // => 0
+
+      console.log(sumReduce(5)); // => 15
+      console.log(sumReduce(10)); // => 55
+      console.log(sumReduce(0)); // => 0
     </script>
   </body>
 </html>