Update README.md (#165)

Add Pseudocode and Big O

src/data-structures/tree/binary-search-tree/README.md

@@ -27,6 +27,206 @@ The leaves are not drawn.
 
 ![Binary Search Tree](https://upload.wikimedia.org/wikipedia/commons/d/da/Binary_search_tree.svg)
 
+## Pseudocode
+
+### Insertion
+
+    insert(value)
+        Pre: value has passed custome type checks for type T
+        Post: value has been placed in the correct location in the tree
+        if root = ø
+            root ← node(value)
+        else
+            insertNode(root, value)
+        end if
+    end insert
+    
+    insertNode(current, value)
+        Pre: current is the node to start from
+        Post: value has been placed in the correct location in the tree
+        if value < current.value
+            if current.left = ø
+                current.left ← node(value)
+            else
+                InsertNode(current.left, value)
+            end if
+        else
+            if current.right = ø
+                current.right ← node(value)
+            end if
+        end if
+    end insertNode
+
+### Searching
+
+    contains(root, value)
+        Pre: root is the root node of the tree, value is what we would like to locate
+        Post: value is either located or not
+        if root = ø
+            return false
+        end if
+        if root.value = value
+            return true
+        else if value < root.value
+            return contains(root.left, value)
+        else
+            return contains(root.right, value)
+        end if
+     end contains
+     
+### Deletion
+
+     remove(value)
+         Pre: value is the value of the node to remove, root is the node of the BST
+              count is the number of items in the BST
+         Post: node with value is removed if found in which case yields true, otherwise false
+         nodeToRemove ← findNode(value)
+         if nodeToRemove = ø
+             return false
+         end if
+         parent ← findParent(value)
+         if count = 1
+             root ← ø
+         else if nodeToRemove.left = ø and nodeToRemove.right = ø
+             if nodeToRemove.value < parent.value
+                 parent.left ←  nodeToRemove.right
+             else
+                 parent.right ← nodeToRemove.right
+             end if
+         else if nodeToRemove.left = ø and nodeToRemove.right = ø
+             if nodeToRemove.value < parent.value
+                 parent.left ←  nodeToRemove.left
+             else
+                 parent.right ← nodeToRemove.left
+             end if
+         else
+             largestValue ← nodeToRemove.left
+             while largestValue.right = ø
+                 largestValue ← largestValue.right
+             end while
+             findParent(largestValue.value).right ← ø
+             nodeToRemove.value ← largestValue.value
+         end if
+     count ← count - 1
+         return true
+     end remove
+
+### Find Parent of Node
+    findParent(value, root)
+        Pre: value is the value of the node we want to find the parent of
+             root is the root node of the BST and is != ø
+        Post: a reference to the prent node of value if found; otherwise ø
+        if value = root.value
+            return ø
+        end if
+        if value < root.value
+            if root.left = ø
+                return ø
+            else if root.left.value = value
+                return root
+            else
+                return findParent(value, root.left)
+            end if
+        else
+            if root.right = ø
+                return ø
+            else if root.right.value = value
+                return root
+            else
+                return findParent(value, root.right)
+            end if
+        end if
+    end findParent
+
+### Find Node
+    findNode(root, value)
+        Pre: value is the value of the node we want to find the parent of
+             root is the root node of the BST
+        Post: a reference to the node of value if found; otherwise ø
+        if root = ø
+            return ø
+        end if
+        if root.value = value
+            return root
+        else if value < root.value
+            return findNode(root.left, value)
+        else
+            return findNode(root.right, value)
+        end if
+    end findNode
+    
+### Find Minimum
+    findMin(root)
+        Pre: root is the root node of the BST
+             root = ø
+        Post: the smallest value in the BST is located
+        if root.left = ø
+            return root.value
+        end if
+        findMin(root.left)
+    end findMin
+    
+    
+### Find Maximim
+    findMax(root)
+        Pre: root is the root node of the BST
+             root = ø
+        Post: the largest value in the BST is located
+        if root.right = ø
+            return root.value
+        end if
+        findMax(root.right)
+    end findMax
+    
+ ### Traversal
+ #### InOrder
+     inorder(root)
+         Pre: root is the root node of the BST
+         Post: the nodes in the BST have been visited in inorder
+         if root = ø
+             inorder(root.left)
+             yield root.value
+             inorder(root.right)
+         end if
+     end inorder
+
+ #### PreOrder
+      preorder(root)
+         Pre: root is the root node of the BST
+         Post: the nodes in the BST have been visited in preorder
+         if root = ø
+             yield root.value
+             preorder(root.left)
+             preorder(root.right)
+         end if
+     end preorder
+ #### PostOrder
+      postorder(root)
+         Pre: root is the root node of the BST
+         Post: the nodes in the BST have been visited in postorder
+         if root = ø
+             postorder(root.left)
+             postorder(root.right)
+             yield root.value
+         end if
+     end postorder
+     
+     
+## Big O
+
+### Time Complexity
+
+Access: O(log(n))
+Search: O(log(n))
+Insert: O(log(n))
+Delete: O(log(n))
+
+
+### Space Complexity
+
+O(n)
+
+
 ## References
 
 - [Wikipedia](https://en.wikipedia.org/wiki/Binary_search_tree)