根据前序和中序，使用JavaScript编写代码得到二叉树
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
var qian = ["a", "b", "d", "e", "c", "f", "g"];
var zhong = ["d", "b", "e", "a", "f", "c", "g"];
function Node(value){
this.value = value;
this.left = null;
this.right = null;
}
//通过前序和中序还原二叉树
function resumeTree(qian, zhong){
if(qian == null || zhong == null || qian.length == 0 || zhong.length == 0 || qian.length != zhong.length) return null;//qian和zhong数组为null或者长度为0，或者两者长度不相等，直接返回
var root = new Node(qian[0]);//前序第一个节点是二叉树的根节点
var index = zhong.indexOf(qian[0]);//找到中序里根节点所在的索引
var zhongLeft = zhong.slice(0, index);//获取中序的左子树
var zhongRight = zhong.slice(index + 1, zhong.length);//获取中序的右子树
var qianLeft = qian.slice(1, index + 1);//获取前序的左子树
var qianRight = qian.slice(index + 1, qian.length);//获取前序的右子树
root.left = resumeTree(qianLeft, zhongLeft);//找到节点的左节点
root.right = resumeTree(qianRight, zhongRight);//找到节点的右节点
return root;//返回二叉树
}
var tree = resumeTree(qian, zhong);//获取二叉树
console.log(tree.left);//打印左子树
console.log(tree.right);//打印右子树
</script>
</body>
</html>
根据中序和后续，使用JavaScript编写代码得到二叉树
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
var hou = ["d", "e", "b", "f", "g", "c", "a"];
var zhong = ["d", "b", "e", "a", "f", "c", "g"];
function Node(value){
this.value = value;
this.left = null;
this.right = null;
}
//通过后序和中序还原二叉树
function resumeTree(hou, zhong){
if(hou == null || zhong == null || hou.length == 0 || hou.length == 0 || hou.length != zhong.length) return null;//hou和zhong数组为null或者长度为0，或者两者长度不相等，直接返回
var root = new Node(hou[hou.length - 1]);//后序最后一个节点是二叉树的根节点
var index = zhong.indexOf(hou[hou.length - 1]);//找到中序里根节点所在的索引
var zhongLeft = zhong.slice(0, index);//获取中序的左子树
var zhongRight = zhong.slice(index + 1, zhong.length);//获取中序的右子树
var houLeft = hou.slice(0, index);//获取后序的左子树
var houRight = hou.slice(index, hou.length - 1);//获取后序的右子树
root.left = resumeTree(houLeft, zhongLeft);//找到节点的左节点
root.right = resumeTree(houRight, zhongRight);//找到节点的右节点
return root;//返回二叉树
}
var tree = resumeTree(hou, zhong);//获取二叉树
console.log(tree.left);//打印左子树
console.log(tree.right);//打印右子树
</script>
</body>
</html>