class TreeNode: def __init__(self,x): self.val = x self.left = None self.right = Nonedef buildTree(preorder, inorder): pre_r = len(preorder)-1 in_r = len(inorder)-1 def buildt(preorder,pre_l,pre_r,inorder,in_l,in_r): if pre_l > pre_r or in_l >in_r: return None ro = preorder[pre_l] cur = in_l while inorder[cur]!=ro: cur+=1 root = TreeNode(ro) root.left = buildt(preorder, pre_l+1, pre_l+cur-in_l, inorder, in_l, cur-1) root.right = buildt(preorder, pre_l+cur-in_l+1, pre_r, inorder, cur+1, in_r) return root return buildt(preorder, 0, pre_r, inorder, 0, in_r)
