Discussion About Construct Parent array Tree

#1

This is Discussion thread about Construct Parent array Tree

#2

when i am complie code its gives InputMismatchException but inputFormate is correct i dont know why this compliation error come.

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import java.util.*;

class TreeNode {
int data;
TreeNode left;
TreeNode right;

TreeNode(int data) {
    this.data = data;
}

}

public class Main {

public static void constractTree(int[] nums) {
    Queue<TreeNode> queue = new LinkedList<>();
    Map<Integer, ArrayList<Integer>> nodeTrack = new HashMap<>();
    for (int i = 0; i < nums.length; i++) {
        if (nodeTrack.containsKey(nums[i])) {
            ArrayList<Integer> nodes = nodeTrack.get(nums[i]);
            nodes.add(i);
        } else {
            ArrayList<Integer> nodes = new ArrayList<>();
            nodes.add(i);
            nodeTrack.put(nums[i], nodes);
        }
    }
    TreeNode rootNode = null;
    if (nodeTrack.containsKey(-1)) {
        ArrayList<Integer> rootList = nodeTrack.get(-1);
        Integer rootData = rootList.get(0);
        TreeNode root = new TreeNode(rootData);
        queue.add(root);
    }
    while (!queue.isEmpty()) {
        TreeNode root = queue.poll();
        if (rootNode == null) {
            rootNode = root;
        }
        if (nodeTrack.containsKey(root.data)) {
            ArrayList<Integer> nodeList = nodeTrack.get(root.data);
            Integer leftData = nodeList.get(0);
            if (nodeList.size() == 2) {
                Integer rightChild = nodeList.get(1);
                TreeNode leftNode = new TreeNode(leftData);
                TreeNode rightNode = new TreeNode(rightChild);
                root.left = leftNode;
                root.right = rightNode;
                queue.add(leftNode);
                queue.add(rightNode);
            } else {
                TreeNode leftNode = new TreeNode(leftData);
                root.left = leftNode;
                queue.add(leftNode);
            }
        }
    }
    preOrder(rootNode);
}

private static void preOrder(TreeNode root) {
    if (root == null) {
        return;
    }
    System.out.print(root.data + " ");
    preOrder(root.left);
    preOrder(root.right);
}


public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int testcase = scanner.nextInt();
    scanner.nextLine();
    for (int i = 0; i < testcase; i++) {
        int n = scanner.nextInt();
        int[] arrayTree = new int[n];
        for (int j = 0; j < arrayTree.length; j++) {
            arrayTree[j] = scanner.nextInt();
        }
        constractTree(arrayTree);
    }
}

}