merge: Let traverseLevel return early if node is null (TheAlgorithms#878)

Author: Worldwidebrine

Trees/BreadthFirstTreeTraversal.js

@@ -19,31 +19,31 @@ class BinaryTree {
 
   breadthFirst () {
     const h = this.getHeight(this.root)
-    for (let i = 1; i <= h; i++) {
+    for (let i = 0; i !== h; i++) {
       this.traverseLevel(this.root, i)
     }
     return this.traversal
   }
 
   // Computing the height of the tree
   getHeight (node) {
-    if (node == null) {
+    if (node === null) {
       return 0
-    } else {
-      const lheight = this.getHeight(node.left)
-      const rheight = this.getHeight(node.right)
-      return lheight > rheight ? lheight + 1 : rheight + 1
     }
+    const lheight = this.getHeight(node.left)
+    const rheight = this.getHeight(node.right)
+    return lheight > rheight ? lheight + 1 : rheight + 1
   }
 
-  traverseLevel (node, level) {
-    if (level === 1 && node !== null) {
+  traverseLevel (node, levelRemaining) {
+    if (node === null) {
+      return
+    }
+    if (levelRemaining === 0) {
       this.traversal.push(node.data)
     } else {
-      if (node !== null) {
-        this.traverseLevel(node.left, level - 1)
-        this.traverseLevel(node.right, level - 1)
-      }
+      this.traverseLevel(node.left, levelRemaining - 1)
+      this.traverseLevel(node.right, levelRemaining - 1)
     }
   }
 }