Refactoring of successor and predecessor methods.

tmorcinek · Sep 9, 2014 · 16af3a4 · 16af3a4
1 parent 0d4febf
commit 16af3a4
Showing 1 changed file with 20 additions and 12 deletions.
diff --git a/src/main/java/com/morcinek/training/data_structures/tree/bst/LinkedBSTree.java b/src/main/java/com/morcinek/training/data_structures/tree/bst/LinkedBSTree.java
@@ -112,37 +112,45 @@ private BSTNode maximumNodeAfter(BSTNode node) {
         return node;
     }
 
+    private T getNodeValue(BSTNode node) {
+        if (node != null) {
+            return node.value;
+        }
+        return null;
+    }
+
     @Override
     public T predecessor(T value) {
+        return getNodeValue(predecessorNode(value));
+    }
+
+    private BSTNode predecessorNode(T value){
         BSTNode node = searchNode(value, root);
         if (node.left != null) {
-            return maximumNodeAfter(node.left).value;
+            return maximumNodeAfter(node.left);
         } else {
             while (node.parent != null && node.parent.right != node) {
                 node = node.parent;
             }
-            return parentNodeValue(node);
+            return node.parent;
         }
     }
 
+
     @Override
     public T successor(T value) {
+        return getNodeValue(successorNode(value));
+    }
+
+    private BSTNode successorNode(T value){
         BSTNode node = searchNode(value, root);
         if (node.right != null) {
-            return minimumNodeAfter(node.right).value;
+            return minimumNodeAfter(node.right);
         } else {
             while (node.parent != null && node.parent.left != node) {
                 node = node.parent;
             }
-            return parentNodeValue(node);
-        }
-    }
-
-    private T parentNodeValue(BSTNode node) {
-        if (node.parent != null) {
-            return node.parent.value;
-        } else {
-            return null;
+            return node.parent;
         }
     }
 }