已知二叉树层次遍历字符串和子节点数，求二叉树

[cff1234]

//输入参数为广度优先算法遍历的二叉树字符串LIST，每个节点对应子节点数LIST。
//
public static TreeNode<String> rebuildFromBFSList(List<String> bfsData, List<Integer> childCounts)
{
// TODO: your code for part (b)
return null;
}



bfsData A B C D E F G
childCounts 6 4 0 0 2 0 0


// A
// / \
// B C
// / \
// D E
// / \
// F G


示例数据如上图所示，求解，不胜感激。

[cff1234]

都没有人会解这道题吗？

[suen.sun]

请问你这个TreeNode是什么样的结构？

[suen.sun]

package com.suen;

public class Node {
	private Node left;
	private Node right;
	private String name;
	private int childs;

	public Node() {

	}

	public Node(String name) {
		this();
		this.name = name;
	}

	public Node(String name, int childs) {
		this(name);
		this.childs = childs;
	}

	public Node getLeft() {
		return left;
	}

	public void setLeft(Node left) {
		this.left = left;
	}

	public Node getRight() {
		return right;
	}

	public void setRight(Node right) {
		this.right = right;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public int getChilds() {
		return childs;
	}

	@Override
	public String toString() {
		return "[name:" + name + ",childs:" + childs + "]";
	}

	public void print(boolean isRoot, String strPreParent, Node parent) {
		String subPreString = "";
		String currentPrev = "";
		if (isRoot) {
			System.out.println(name);
			if (this.left != null && this.right != null) {
				this.left.print(false, subPreString, this);
				this.right.print(false, subPreString, this);
			}
		} else {// ┠┃┗
			if (parent.left == this) {
				currentPrev = "┠";
				subPreString = "┃";				
			} else if (parent.right == this) {
				currentPrev = "┗";
				subPreString = "　";
			}
			
			System.out.println(strPreParent + currentPrev + name);
			if (this.left != null && this.right != null) {
				subPreString = strPreParent + subPreString;
				this.left.print(false, subPreString, this);
				this.right.print(false, subPreString, this);
			}
		}
	}

}

package com.suen;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

public class BFS_Recover {
	/**
	 * @param bfsData
	 * @param childCounts
	 * @return
	 */
	public static Node rebuildFromBFSList(List<String> bfsData,
			List<Integer> childCounts) {
		List<Node> nodes = new ArrayList<Node>();
		for (String s : bfsData) {
			Node node = new Node(s, childCounts.get(bfsData.indexOf(s)));
			System.out.println(node.getName() + "\t" + node.getChilds());
			nodes.add(node);
		}
		List<Node> parentTempNodeList = new ArrayList<Node>();
		List<Node> subTempNodeList = new ArrayList<Node>();
		List<Node> exchangeNodeList = new ArrayList<Node>();
		Node root = nodes.get(0);
		parentTempNodeList.add(root);
		nodes.remove(0);

		do {
			int cnt = 0;
			for (int i = 0; i < parentTempNodeList.size(); i++) {
				Node node = parentTempNodeList.get(i);
				if (node.getChilds() >= 2) {
					cnt += 2;
				}
			}

			for (int i = 0; i < cnt; i++) {
				subTempNodeList.add(nodes.get(0));
				nodes.remove(0);
			}
			exchangeNodeList = null;
			exchangeNodeList = Arrays.asList(subTempNodeList
					.toArray(new Node[] {}));
			for (int i = 0; i < parentTempNodeList.size(); i++) {
				Node node = parentTempNodeList.get(i);
				if (node.getChilds() >= 2) {
					node.setLeft(subTempNodeList.get(0));
					node.setRight(subTempNodeList.get(1));
					subTempNodeList.remove(0);
					subTempNodeList.remove(0);
				}
			}
			subTempNodeList.clear();
			parentTempNodeList = Arrays.asList(exchangeNodeList
					.toArray(new Node[] {}));
		} while (nodes.size() > 0);
		return root;
	}

	public static void main(String[] args) {
		List<String> bfsData = new ArrayList<String>();
		List<Integer> childCounts = new ArrayList<Integer>();

		bfsData.add("A");
		bfsData.add("B");
		bfsData.add("C");
		bfsData.add("D");
		bfsData.add("E");
		bfsData.add("F");
		bfsData.add("G");
		childCounts.add(6);
		childCounts.add(4);
		childCounts.add(0);
		childCounts.add(0);
		childCounts.add(2);
		childCounts.add(0);
		childCounts.add(0);
		Node root = rebuildFromBFSList(bfsData, childCounts);
		System.out.println();
		root.print(true, "", null);
	}
}

A 6
B 4
C 0
D 0
E 2
F 0
G 0

A
┠B
┃┠D
┃┗E
┃　┠F
┃　┗G
┗C

[suen.sun]

不知道是楼主是否想要上面的结果。

[cff1234]

非常感谢，要的就是这样的结果。