diff --git a/src/Traversal.java b/src/Traversal.java index 8da0f79..d4499d3 100644 --- a/src/Traversal.java +++ b/src/Traversal.java @@ -1,5 +1,171 @@ +import java.util.HashMap; +import java.util.LinkedList; +import java.util.Map; +import java.util.Queue; +import java.util.Stack; + public class Traversal { public static void main(String[] args) { + TreeNode root = new TreeNode (10, null, null); + root.left = new TreeNode (9, null,null); + root.left.left = new TreeNode (5, null,null); + root.left.right = new TreeNode (2, null,null); + + root.right = new TreeNode (15, null, null); + root.right.left = new TreeNode (-3, null, null); + root.right.right = new TreeNode (5, null, null); + root.right.right.right = new TreeNode (22, null, null); + + + TreeNode stringRoot = new TreeNode ("Hello", null, null); + stringRoot.left = new TreeNode ("how", null,null); + stringRoot.left.left = new TreeNode ("Hello", null,null); + stringRoot.left.right = new TreeNode ("you", null,null); + + stringRoot.right = new TreeNode ("I", null, null); + stringRoot.right.left = new TreeNode ("am", null, null); + stringRoot.right.right = new TreeNode ("am", null, null); + stringRoot.right.right.right = new TreeNode ("good", null, null); + + TreeNode megaRoot = new TreeNode(1, null, null); + + TreeNode current = megaRoot; + + for(int i =2; i <= 5000; i++){ + current.right = new TreeNode(i, null, null); + current = current.right; + } + + levelOrder(root); + //preOrderIter(megaRoot); + + // System.out.println("Preorder recursive"); + // preorder(root); + // System.out.println("Preorder Iterativr"); + // preOrderIter(root); + + //preorder(root); + //postorder(root); + //inorder(root); + + //printGreater(root, 4); + //System.out.println(countNodes(root)); + + //System.out.println(toMap(stringRoot)); + + } + + // Print a tree rooted at the given node in pre-order + public static void preorder(TreeNode node){ + //if null, return + if(node == null) return; + //print value + System.out.println(node.value); + //traverse left to recursion and tree works + preorder(node.left); + //traverse right + preorder(node.right); + + } + + public static void preOrderIter(TreeNode node){ + Stack> stack = new Stack<>(); + + stack.push(node); + + while(!stack.empty()){ + TreeNode current = stack.pop(); + + if(current == null){ + continue; + } + System.out.println(current.value); + stack.push(current.right); + stack.push(current.left); + + + + } + } + + public static void levelOrder(TreeNode node){ + Queue> queue = new LinkedList<>(); + + queue.add(node); + + while(!queue.isEmpty()){ + TreeNode current = queue.poll(); + + if(current == null){ + continue; + } + System.out.println(current.value); + queue.add(current.left); + queue.add(current.right); + + + } + } + + + public static Map toMap(TreeNode node) { + Map counts = new HashMap<>(); + toMap(node, counts); + return counts; + + } + //overloading and helper method + + private static void toMap(TreeNode node, Map counts ) { + + if(node == null) { + return; + } + //fill up those counts + counts.put(node.value, counts.getOrDefault(node.value, 0) +1); + toMap(node.left, counts); + toMap(node.right, counts); + + + } + + public static int countNodes(TreeNode node) { + //if(node == null) return 0; + return node == null ? 0: countNodes(node.left) + countNodes(node.right) + 1; + // int leftCount = countNodes(node.left); + // int rightCount = countNodes(node.right); + // int overallCount = leftCount + rightCount + 1; + + // return overallCount; + + } + + public static void printGreater(TreeNode node, int threshold) { + if(node == null) return; + if(node.value > threshold) { + System.out.println(node.value); + } + printGreater(node.left, threshold); + printGreater(node.right, threshold); + } + + + + + public static void postorder(TreeNode node){ + if(node == null) return; + postorder(node.left); + postorder(node.right); + // print after recursion + System.out.println(node.value); + } + + public static void inorder(TreeNode node){ + if(node == null) return; + inorder(node.left); + System.out.println(node.value); + inorder(node.right); + } } diff --git a/src/TreeNode.java b/src/TreeNode.java index acd9639..9c088e6 100644 --- a/src/TreeNode.java +++ b/src/TreeNode.java @@ -1,4 +1,15 @@ -public class TreeNode { +public class TreeNode { + public T value; + public TreeNode left; + public TreeNode right; + + + public TreeNode (T value, TreeNode left, TreeNode right){ + this.value = value; + this.left = left; + this.right= right; + + } } \ No newline at end of file