leetcode-105 从前序与中序遍历序列构造二叉树

105. 从前序与中序遍历序列构造二叉树

难度: 中等

---

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func buildTree(preorder []int, inorder []int) *TreeNode {

    var root *TreeNode

    if len(preorder) < 1 || len(inorder) < 1{
        return root
    }

    left := find(inorder,preorder[0])

    if left < 0{
        return root
    }

    root = &TreeNode{
        Val:preorder[0],
        Left:buildTree(preorder[1:left+1],inorder[0:left]),
        Right:buildTree(preorder[left+1:],inorder[left+1:]),
    }
    return root
}


func find(inorder []int,target int) int {


    for i := 0; i < len(inorder);i++ {

        if  target == inorder[i] {
            return i
        }
    }

    return -1
}

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原文链接: https://dashen.tech/2015/03/01/leetcode-105-从前序与中序遍历序列构造二叉树/

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