The depth of the print data by the binary tree node

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This link: https://blog.csdn.net/red_sheeps/article/details/80614307

Today's headlines today to interview, was asked a question about the binary tree itself is not good at arithmetic, the results like a long thought out solutions, after reminding the interviewer did he realize, came back immediately written out to achieve, see below.

Interview questions

This problem is, as a binary tree, and then printing press depth, it should be 1,2,3,4,5,6,7

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This is what you can expect recursion, no problem, Papa Pa achieve a pass out to achieve real results printout is: 1,2,4,5,3,6,7, it failed to achieve. Later, the interviewer said to each of the elements are stored recursively, he thought for a moment back will achieve written out, as indicated below.

Code

Node node class

Very simple, nothing to say.

class Node {
    int value;
    Node left;
    Node right;

    public Node(int value, Node left, Node right) {
        this.value = value;
        this.left = left;
        this.right = right;
    }
}

The main logical approach

    private static void printNode(List<Node> nodes) {
        List<Node> listT = new ArrayList<>();
        for (Node node : nodes) {
            System.out.print(node.value + ",");
            if (node.left != null) {
                listT.add(node.left);
            }
            if (node.right != null) {
                listT.add(node.right);
            }
        }
        // 判断当前层是否有节点加入listT中，如果有，则进行递归调用
        if(!listT.isEmpty()) {
            printNode(listT);
        }
    }

To achieve the main method

    public static void main(String[] args) {
        // leaf node
        Node node4 = new Node(4, null, null);
        Node node5 = new Node(5, null, null);
        Node node6 = new Node(6, null, null);
        Node node7 = new Node(7, null, null);

        // node 2 and node 3
        Node node2 = new Node(2, node4, node5);
        Node node3 = new Node(3, node6, node7);

        // root node
        Node root = new Node(1, node2, node3);
        List<Node> list = new ArrayList<>();
        list.add(root);
        printNode(list);
    }

Execution results are as follows

to sum up

For face questions binary tree, under normal circumstances, are inseparable from recursion, and then think about what each recursive role is, I like this question is the role of each node, because of the need to print the data by layer. If you navigate to a recursive role, think logically achieve much better.
We hope to give two faces of the opportunity ah.