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代码如下，有没有大佬能讲一下构造二叉树的思路是什么，想了一上午没想明白

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func buildTree(inorder []int, postorder []int) *TreeNode {
    if len(postorder) == 0 {
        return nil
    }
    root := &TreeNode{Val: postorder[len(postorder)-1]}
    stack := []*TreeNode{root}
    inorderIndex := len(inorder) - 1
    for i := len(postorder) - 2; i >= 0; i-- {
        postorderVal := postorder[i]
        node := stack[len(stack)-1]
        if node.Val != inorder[inorderIndex] {
            node.Right = &TreeNode{Val: postorderVal}
            stack = append(stack, node.Right)
        } else {
            for len(stack) > 0 && stack[len(stack)-1].Val == inorder[inorderIndex] {
                node = stack[len(stack)-1]
                stack = stack[:len(stack)-1]
                inorderIndex--
            }
            node.Left = &TreeNode{Val: postorderVal}
            stack = append(stack, node.Left)
        }
    }      
    return root
}