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好帮手慕言

2021-07-20

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同学你好，本站的教学服务只包含站内视频内容问题解答、站内习题问题解答、站内作业问题解答、站内测试题问题解答以及站内产品使用问题解答。故同学的问题不包含在教学服务内，本次老师破例为同学讲解一下，下不为例哦。

针对同学的问题，解答如下：

1、二叉树是一种特殊的树，表现在它的子节点个数不超过两个。且二叉树的子树有左右之分，节点结构至少有三部分组成，如下图所示：

data是节点的值，left指向左子节点，right指向右子节点，映射到同学提供的这个图，以A为例，data表示的是A，left指向B节点，right指向D节点。

代码参考：

 function TreeNode(val) {
            this.val = val
            this.left = null
            this.right = null
        }

        let tree = new TreeNode('A')
        let nodeB = new TreeNode('B')
        let nodeC = new TreeNode('C')
        let nodeD = new TreeNode('D')
        let nodeE = new TreeNode('E')
        let nodeF = new TreeNode('F')
        let nodeG = new TreeNode('G')
        let nodeH = new TreeNode('H')
        let nodeI = new TreeNode('I')
        let nodeJ = new TreeNode('J')

        tree.left = nodeB
        tree.right = nodeD

        nodeB.left = nodeC
        nodeB.right = nodeE

        nodeD.left = nodeF
        nodeD.right = nodeG

        nodeE.left = nodeH
        nodeE.right = nodeI

        nodeG.left = nodeJ

2、printTree函数实现可以参考下方：

 <script>
        function TreeNode(val) {
            this.val = val
            this.left = null
            this.right = null
        }

        let tree = new TreeNode('A')
        let nodeB = new TreeNode('B')
        let nodeC = new TreeNode('C')
        let nodeD = new TreeNode('D')
        let nodeE = new TreeNode('E')
        let nodeF = new TreeNode('F')
        let nodeG = new TreeNode('G')
        let nodeH = new TreeNode('H')
        let nodeI = new TreeNode('I')
        let nodeJ = new TreeNode('J')

        tree.left = nodeB
        tree.right = nodeD

        nodeB.left = nodeC
        nodeB.right = nodeE

        nodeD.left = nodeF
        nodeD.right = nodeG

        nodeE.left = nodeH
        nodeE.right = nodeI

        nodeG.left = nodeJ


        function printTree(tree) {
            let currentLevel = 1
            // 存放节点
            let stack = []
            // 把tree放到数组中
            stack.push(tree)
            // 最终的结果数组
            let result = []
            // 判断stack里有没有内容
            while (stack.length > 0) {
                let text = currentLevel.toString()
                let count = stack.length
                // 判断数组的长度
                while (count > 0) {
                    // 取到数组的第一项
                    let node = stack.shift()
                    // text与node.val拼接
                    text += node.val
                    // 如果有左右节点，就存到stack中
                    if (node.left) {
                        stack.push(node.left)
                    }
                    if (node.right) {
                        stack.push(node.right)
                    }
                    count -= 1
                }
                result.push(text)
                currentLevel += 1
            }
            // 把结果返回
            return result.join("\n")
        }
        console.log(printTree(tree))
    </script>

不明白的地方可以打印在控制台看结果，另外：如果想了解二叉树相关知识，可以在站内搜索一下。祝学习愉快~

0

hq_Unique彼岸花丶花海_0

hp>好的谢谢老师

h021-07-20

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