// Helene Martin, CSE 143
// An IntSearchTree object represents an entire binary search tree of ints.
// Class invariants: 
//    - nodes to the left of a root have smaller values
//    - nodes to the right of a root have larger values
//    - there are no duplicates

import java.util.NoSuchElementException;

public class IntSearchTree {
   private IntTreeNode overallRoot;

   // Constructs an empty binary search tree.
   public IntSearchTree() {
      overallRoot = null;
   }

   // Removes all nodes without children (leaves) in this tree.
   public void removeLeaves() {
      overallRoot = removeLeaves(overallRoot);
   }

   // Removes all leaf nodes in the tree with the given root.
   private IntTreeNode removeLeaves(IntTreeNode root) {
      if (root != null) {
         if (root.left == null && root.right == null) {
            root = null;
         } else {
            root.left = removeLeaves(root.left);
            root.right = removeLeaves(root.right);
         }
      }
      return root;
   }

   // Returns the minimum value from this BST.
   // Throws a NoSuchElementException if the tree is empty.
   public int getMin() {
      if (overallRoot == null) {
         throw new NoSuchElementException();
      }
      return getMin(overallRoot);
   }

   // Returns the minimum value from the BST with the given root.
   // Pre: root is not null
   private int getMin(IntTreeNode root) {
      if (root.left == null) {
         return root.data;
      } else {
         return getMin(root.left);
      }
   }

   // Removes the node with the given value from this BST.
   public void remove(int value) {
      overallRoot = remove(overallRoot, value);
   }

   private IntTreeNode remove(IntTreeNode root, int value) {
      if (root != null) {
         if (value < root.data) {
            root.left = remove(root.left, value);
         } else if (value > root.data) {
            root.right = remove(root.right, value);
         } else { // found it!
            // leaf node case is same as removeLeaves
            // (not necessary to have as a separate case!)
            if (root.left == null && root.right == null) {
               root = null;
            } else if (root.right == null) { // left child only
               root = root.left;
            } else if (root.left == null) { // right child only;
               root = root.right;
            } else {
               int newRoot = getMin(root.right);
               remove(newRoot);
               root.data = newRoot;
            }
         }
      }
      return root;
   }

   // Returns the number of nodes in this tree.
   public int size() {
      return size(overallRoot);
   }

   // Returns the number of nodes in the subtree with root as its root node.
   private int size(IntTreeNode root) {
      if (root == null) {
         return 0;
      } else {
         return 1 + size(root.left) + size(root.right);
      }
   }

   // Returns true if the value is in this tree, false otherwise.
   public boolean contains(int value) {
      return contains(overallRoot, value);
   }

   // Returns true if the value is in the tree starting at the
   // specified root.
   private boolean contains(IntTreeNode root, int value) {
      if (root == null) {
         return false;
      } else if (root.data == value) {
         return true;
      } else if (value < root.data) {
         return contains(root.left, value);
      } else {
         return contains(root.right, value);
      }
   }

   // Adds the given value to this BST.
   // Post: the tree is still a valid BST
   public void add(int value) {
      overallRoot = add(overallRoot, value);
   }

   // Adds the given value to the BST starting at the given root.
   // Post: the tree is still a valid BST
   private IntTreeNode add(IntTreeNode root, int value) {
      if (root == null) {
         root = new IntTreeNode(value);
      } else if (value < root.data) {
         root.left = add(root.left, value);
      } else if (value > root.data) {
         root.right = add(root.right, value);
      }
      return root;
   }

   // Prints a pre-order traversal of this tree.
   public void printPreorder() {
      printPreorder(overallRoot);
   }

   // Prints a pre-order traversal of the tree starting at the specified root
   private void printPreorder(IntTreeNode root) {
      // implicit base case: do nothing when we reach a null root
      if (root != null) {
         System.out.print(root.data + " ");
         printPreorder(root.left);
         printPreorder(root.right);
      }
   }

   // Prints an in-order traversal of this tree.
   public void printInorder() {
      printInorder(overallRoot);
   }

   // Prints an in-order traversal of the tree starting at the specified root
   private void printInorder(IntTreeNode root) {
      if (root != null) {
         printInorder(root.left);
         System.out.print(root.data + " ");
         printInorder(root.right);
      }
   }

   // Prints a post-order traversal of this tree.
   public void printPostorder() {
      printPostorder(overallRoot);
   }

   // Prints a post-order traversal of the tree starting at the specified root
   private void printPostorder(IntTreeNode root) {
      if (root != null) {
         printPostorder(root.left);
         printPostorder(root.right);
         System.out.print(root.data + " ");
      }
   }

   // Prints the tree contents, one per line, following an inorder
   // traversal and using indentation to indicate node depth; prints
   // right to left so that it looks correct when the output is rotated.
   public void printSideways() {
      printSideways(overallRoot, 0);
   }

   // Prints in reversed preorder the tree with given root, indenting
   // each line to the given level
   private void printSideways(IntTreeNode root, int level) {
      if (root != null) {
         printSideways(root.right, level + 1);
         for (int i = 0; i < level; i++) {
            System.out.print("    ");
         }
         System.out.println(root.data);
         printSideways(root.left, level + 1);
      }
   }
}