def dfs(l, r):
if l > r: return None
mid = (r - l) // 2 + l
root = TreeNode(nums[mid])
root.left = dfs(l, mid - 1)
root.right = dfs(mid + 1, r)
return root
def dfs(pl, pr, il, ir):
if pl > pr: return None
n = TreeNode(preorder[pl])
if pl == pr: return n
mid = inord_map[n.val]
n.left = dfs(pl + 1, pl + (mid - il), il, mid - 1)
n.right = dfs(pl + (mid - il) + 1, pr, mid + 1, il)
return n
def dfs(pl, pr, il, ir):
if pl > pr: return None
node = TreeNode(postorder[pr])
if pl == pr: return node
inord_mid = inord_map[node.val]
postord_mid = pr - (ir - inord_mid)
node.left = dfs(pl, postord_mid - 1, il, inord_mid - 1)
node.right = dfs(postord_mid, pr - 1, inord_mid + 1, ir)
return node