有中序遍历和后序遍历构建二叉树

 

 

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/**  * Definition for a binary tree node.  * type TreeNode struct {  *     Val int  *     Left *TreeNode  *     Right *TreeNode  * }  */ func buildTree(inorder []int, postorder []int) *TreeNode {     return build(inorder,0,len(inorder)-1,postorder,0,len(postorder)-1) }   func build(inorder []int,s1,e1 int,postorder []int,s2,e2 int)*TreeNode{     if s1>e1{         return nil     }     //根节点的值肯定是后序遍历的最后一个节点     rootVal:=postorder[e2]     //在中序遍历结果里查找根节点的索引     inIdx:=s1     for i:=s1;i<e1;i++{         if rootVal==inorder[i]{             inIdx=i             break         }     }     //构造根节点     root:=&TreeNode{}     root.Val=rootVal     //递归构造左右子树     leftSize:=inIdx-s1     root.Left=build(inorder,s1,inIdx-1,postorder,s2,s2+leftSize-1)     root.Right=build(inorder,inIdx+1,e1,postorder,s2+leftSize,e2-1)     return root }