Merge pull request #76 from g-palmer/checkBST

binary search tree check

Author: blakeembrey

binary-search-tree-check/binary-search-tree-check-alt.js

@@ -0,0 +1,26 @@
+// depth first traversal checking sort order of each node's value against previous
+
+var isBinarySeachTree = function(bst) {
+  // reference to previous node value
+  var prev;
+
+  // return IIFE of recursive bst traversal
+  return (function isBST(bst) {
+
+    // if left, check left and break if necessary
+    if ( bst.left && !isBST(bst.left) ) { return false; }
+
+    // break if current node value is less than previous
+    if ( bst.value < prev ) { return false; }
+
+    // set previous to current node value
+    prev = bst.value;
+
+    // if right, check right and break if necessary
+    if (bst.right && !isBST(bst.right) ) { return false; }
+
+    // passes test
+    return true;
+
+  })(bst);
+};