# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def diameterOfBinaryTree(self, root):
"""
:type root: TreeNode
:rtype: int
"""
def helper(root):
if not root:
return 0, 0
lr, ll = helper(root.left)
rr, rl = helper(root.right)
return max(lr, rr, ll + rl), max(ll, rl) + 1
return helper(root)[0]
import utils
t = utils.maketree([1, 2, 3, 4, 5])
print Solution().diameterOfBinaryTree(t)
# self.left = None
# self.right = None
class Solution(object):
def __init__(self):
self.res = float('-inf')
def maxPathSum(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if not root: return 0
def maxPathSumHelper(root):
if not root: return float('-inf')
lm = max(0, maxPathSumHelper(root.left))
rm = max(0, maxPathSumHelper(root.right))
self.res = max(self.res, root.val + lm + rm)
return max(root.val + lm, root.val + rm)
maxPathSumHelper(root)
return self.res
import utils
print Solution().maxPathSum(utils.maketree([2, 1, 3]))
# self.val = x # self.left = None # self.right = None class Solution(object): def kthSmallest(self, root, k): """ :type root: TreeNode :type k: int :rtype: int """ def kthSmallestHelper(root, k): # print 'kthSmallestHelper', root, root.val if root else -1, k if not root: return None, 0 val, leftsize = kthSmallestHelper(root.left, k) # print 'k', k, 'val', val if val is not None: return val, 0 if leftsize == k-1: return root.val, 0 else: val, rightsize = kthSmallestHelper(root.right, k - leftsize - 1) if val is not None: return val, 0 else: return None, leftsize+1+rightsize return kthSmallestHelper(root, k)[0] import utils print Solution().kthSmallest(utils.maketree([2,1]), 2)
# self.val = x # self.left = None # self.right = None class Solution(object): def postorderTraversal(self, root): """ :type root: TreeNode :rtype: List[int] """ if not root: return [] stack = [] stack.append((1, root)) postorder = [] while stack: op, root = stack.pop() if op == 1: stack.append((2, root)) if root.right: stack.append((1, root.right)) if root.left: stack.append((1, root.left)) else: postorder.append(root.val) return postorder import utils print Solution().postorderTraversal(utils.maketree([1,None,2,3]))
# self.val = x
# self.left = None
# self.right = None
class Solution:
# @param root, a tree node
# @return a boolean
def isSymmetric(self, root):
if root is None: return True
return self.solve(root.left, root.right)
def solve(self, left, right):
if left is None and right is None:
return True
if left is None or right is None:
return False
if left.val != right.val:
return False
return self.solve(left.left, right.right) and self.solve(
left.right, right.left)
import utils as u
print Solution().isSymmetric(u.maketree([1, 2, 2, 3, 4, 4, 3]))
print Solution().isSymmetric(u.maketree([1, 2, 2, None, 3, None, 3]))
while q: qsize = len(q) head = tail = ListNode(None) for i in xrange(qsize): treenode = q.popleft() node = ListNode(treenode.val) tail.next = node tail = node if treenode.left: q.append(treenode.left) if treenode.right: q.append(treenode.right) linkedLists.append(head.next) return linkedLists import utils # 5 # 4 7 # 3 6 8 root = utils.maketree([1, 2, 2, None, 3, None, 3]) utils.printtree(root) lists = getLevels(root) for l in lists: utils.printlist(l )
from collections import Counter class Solution(object): def findFrequentTreeSum(self, root): """ :type root: TreeNode :rtype: List[int] """ if not root: return [] sums = Counter() def postorder(root): ls, rs = 0, 0 if root.left: ls = postorder(root.left) if root.right: rs = postorder(root.right) # visit root now s = root.val + ls + rs sums[s] += 1 return s postorder(root) maxSumCount = max(sums.itervalues()) return [s for s, c in sums.iteritems() if c == maxSumCount] import utils print Solution().findFrequentTreeSum(utils.maketree([5, 2, -3]))
ll, lr = None, None
if root.right:
rl, rr = root.right.left, root.right.right
else:
rl, rr = None, None
l, r = root.left, root.right
c = min(min(l._c, l._noc) if l else 0, (min(ll._c, ll._noc) if ll else 0) + (min(lr._c, lr._noc) if lr else 0)) + \
min(min(r._c, r._noc) if r else 0, (min(rl._c, rl._noc) if rl else 0) + (min(rr._c, rr._noc) if rr else 0)) + 1
if not l and not r:
noc = INF
elif not l: # must r
noc = r._c
elif not r: # must l
noc = l._c
else: # must l and r
noc = min(l._c + min(r._c, r._noc), r._c + min(l._c, l._noc))
root._c, root._noc = c, noc
solve(root)
return min(root._c, root._noc)
import utils
null = None
root = utils.maketree(
[0, null, 0, null, 0, null, 0, null, 0, 0, 0, null, null, 0, 0])
print Solution().minCameraCover(root)
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def invertTree(self, root):
"""
:type root: TreeNode
:rtype: TreeNode
"""
if not root: return root
root.right, root.left = self.invertTree(root.left), self.invertTree(
root.right)
return root
import utils
t = utils.maketree([1, 2, 7, 1, 3, 6, 9])
utils.printtree(t)
t = Solution().invertTree(t)
utils.printtree(t)
root.left = self.deleteNode(root.left, key) elif key > root.val: root.right = self.deleteNode(root.right, key) else: # root.val == key, removing root ... if root.left is None: root = root.right elif root.right is None: root = root.left else: # both left and right is non-empty root.val = self.deleteLeftMostNode(root.right, root) print 'delete', root.val return root def deleteLeftMostNode(self, root, parent): node = root isParentLeft = False while node.left: parent = node node = node.left isParentLeft = True if isParentLeft: parent.left = node.right else: parent.right = node.right return node.val from utils import printtree, maketree printtree(Solution().deleteNode(maketree([5,3,6,2,4,None,7]), 3))
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def __init__(self):
self.sum = 0
def convertBST(self, root):
"""
:type root: TreeNode
:rtype: TreeNode
"""
def revorder(root):
if not root: return
revorder(root.right)
# handle root here
# print self.sum, root.val
self.sum = root.val = self.sum + root.val
revorder(root.left)
revorder(root)
return root
import utils
utils.printtree(Solution().convertBST(utils.maketree([5, 2, 13])))
if node.left:
postorder(node.left)
if node.right:
postorder(node.right)
node._sum = (node.left._sum if node.left else
0) + node.val + (node.right._sum if node.right else 0)
node._size = (node.left._size if node.left else
0) + 1 + (node.right._size if node.right else 0)
postorder(root)
return self.solve(root)
def solve(self, root):
ret = 0
if root.left:
ret += self.solve(root.left)
lsize, lsum = root.left._size, root.left._sum
ret += abs(lsum - lsize)
if root.right:
ret += self.solve(root.right)
rsize, rsum = root.right._size, root.right._sum
ret += abs(rsum - rsize)
return ret
import utils
print Solution().distributeCoins(utils.maketree([3, 0, 0]))
def rob(self, root):
"""
:type root: TreeNode
:rtype: int
"""
return self.solve(root, False)
def solve(self, root, isParentRobed):
if not root: return 0
if isParentRobed:
if hasattr(root, 'v1'): return root.v1
else:
if hasattr(root, 'v2'): return root.v2
if isParentRobed:
ret = self.solve(root.left, False) + self.solve(root.right, False)
root.v1 = ret
else:
v1 = self.solve(root.left, False) + self.solve(root.right, False)
v2 = root.val + self.solve(root.left, True) + self.solve(
root.right, True)
ret = max(v1, v2)
root.v2 = ret
return ret
print Solution().rob(utils.maketree([3, 2, 3, None, 3, None, 1]))
print Solution().rob(utils.maketree([3, 4, 5, 1, 3, None, 1]))
# utils.printtree(utils.maketree( [3, 4, 5, 1, 3, None, 1] ))
h.update(lh+str(root.val)+rh)
root.hash = h.digest()
# print root.hash
return root.hash
makehash(s)
makehash(t)
def isEqual(t1, t2):
if not t1 and not t2:
return True
elif not t1 or not t2:
return False
else:
return t1.hash == t2.hash
if isEqual(s, t): return True
return s is not None and (self.isSubtree(s.left, t) or self.isSubtree(s.right, t))
import utils
null = None
s = utils.maketree(
[1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,2]
)
t = utils.maketree([1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,2]
)
utils.printtree(s)
utils.printtree(t)
print Solution().isSubtree(s, t)
self.stk.pop() # pop cur
while True:
if not self.stk:
parent = None
break
parent = self.stk[-1]
if parent.left == cur:
break
cur = parent
self.stk.pop()
# found parent with parent.left == cur
cur = parent
self.cur = cur
if self.stk:
assert self.cur == self.stk[-1]
else:
assert self.cur is None
# print 'movetonext', cur
import utils
t = utils.maketree([1, None, 2])
it = BSTIterator(t)
while it.hasNext():
print it.next()
:type sum: int
:rtype: int
"""
return self.pathSumHelper(root, sum, False)
def pathSumHelper(self, root, sum, pathStarted):
if not root:
return 0
n = 0
if root.val == sum:
# print root.val, sum
n += 1
if root.left:
n += self.pathSumHelper(root.left, sum - root.val, True)
if not pathStarted:
n += self.pathSumHelper(root.left, sum, False)
if root.right:
n += self.pathSumHelper(root.right, sum - root.val, True)
if not pathStarted:
n += self.pathSumHelper(root.right, sum, False)
return n
import utils
t = utils.maketree([10, 5, -3, 3, 2, None, 11, 3, -2, None, 1])
print Solution().pathSum(t, 8)
# @param root, a tree node
# @return an integer
def maxPathSum(self, root):
if root is None: return 0
return self.solve(root)[0]
def solve(self, root):
if root.left is None and root.right is None:
return root.val, root.val
if root.right is None:
LS = self.solve(root.left)
maxsum = max(LS[0], LS[1] + root.val, root.val)
tothis = max(root.val + LS[1], root.val)
elif root.left is None:
RS = self.solve(root.right)
maxsum = max(RS[0], RS[1] + root.val, root.val)
tothis = max(root.val + RS[1], root.val)
else:
LS = self.solve(root.left)
RS = self.solve(root.right)
maxsum = max(LS[0], RS[0], LS[1] + RS[1] + root.val,
LS[1] + root.val, RS[1] + root.val, root.val)
tothis = max(root.val + max(LS[1], RS[1]), root.val)
# print maxsum, tothis
return maxsum, tothis
print Solution().maxPathSum(u.maketree([2, -1]))
