diff --git a/src/Traversal.java b/src/Traversal.java index 8da0f79..5da889b 100644 --- a/src/Traversal.java +++ b/src/Traversal.java @@ -1,5 +1,144 @@ +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("are", 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("doing", 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 <= 50000; i++){ + current.right = new TreeNode(i, null, null); + current = current.right; + } + + // System.out.println("PreOrder recursive"); + // preorder(root); + // System.out.println("PreOrder iterative"); + // preOrderIter(root); + + levelOrder(megaRoot); + + //preorder(root); + //postorder(root); + //centralorder(stringRoot); + + //printGreater(root, 10); + //System.out.println(countNodes(stringRoot)); + + //System.out.println(toMap(stringRoot)); + } + + // Print a tree rooted at the given node in pre order + public static void preorder(TreeNode node){ + if(node == null) return; + System.out.println(node.value); + preorder(node.left); + 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 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 Map toMap(TreeNode node){ + Map counts = new HashMap<>(); + toMap(node, counts); + return counts; + } + + 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){ + return node == null ? 0 : countNodes(node.left) + countNodes(node.right) + 1; + + // if(node == null) return 0; + // int leftCount = countNodes(node.left); + // int rightCount= countNodes(node.right); + // int overallCount = leftCount + rightCount + 1; + // return overallCount; + } + + public static void postorder(TreeNode node){ + if(node == null) return; + postorder(node.left); + postorder(node.right); + System.out.println(node.value); + } + public static void centralorder(TreeNode node){ + if(node == null) return; + centralorder(node.left); + System.out.println(node.value); + centralorder(node.right); } } diff --git a/src/TreeNode.java b/src/TreeNode.java index acd9639..19d9315 100644 --- a/src/TreeNode.java +++ b/src/TreeNode.java @@ -1,4 +1,12 @@ -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