給定乙個二叉樹，找到從根節點到葉子節點的和與給定目標相等的路徑
從根節點開始，遍歷每一條路徑，每走過乙個節點，就把目標值減去這個節點的值，當最後乙個節點沒有左右孩子且這個節點的值等於剩餘的目標值，就返回這個路徑，用乙個區域性list存當前路徑。
def
sum(self,target)
:return self.sum_helper(self.root,target)
defsum_helper
(self,node,target)
:if node is
none
:return
false
if node._left is
none
and node._right is
none
and node._item == target:
#if node._item == target:
return
true
target = target - node._item
return self.sum_helper(node._left,target)
or self.sum_helper(node._right,target)
defsum_road
(self,target)
:return self.sum_target_helper(self.root,target)
defsum_target_helper
(self,node,target)
:if node is
none
:return
res =
self.dfs(node,target,
,res)
return res
defdfs(self,node,target,ls,res)
:if node._left is
none
and node._right is
none
and node._item == target:
if node._left:
self.dfs(node._left,target-node._item,ls+
[node._item]
,res)
if node._right:
self.dfs(node._right,target-node._item,ls+
[node._item]
,res)
def
sum(self,target)
:return self.sum_helper(self.root,target)
defsum_helper
(self,node,target)
:if node is
none
:return
false
#if node._left is none and node._right is none and node._item == target:
if node._item == target:
return
true
target = target - node._item
return self.sum_helper(node._left,target)
or self.sum_helper(node._right,target)
defsum_road
(self,target)
:return self.sum_road_all(self.root,target)
#return self.sum_target_helper(self.root,target)
defsum_road_all
(self,node,target)
:if node is
notnone
:return self.sum_target_helper(node,target)
+self.sum_target_helper(node._left,target)
+self.sum_target_helper(node._right,target)
defsum_target_helper
(self,node,target)
:if node is
none
:return
res =
self.dfs(node,target,
,res)
return res
defdfs(self,node,target,ls,res)
:# if node._left is none and node._right is none and node._item == target:
if node._item == target:
if node._left:
self.dfs(node._left,target-node._item,ls+
[node._item]
,res)
if node._right:
self.dfs(node._right,target-node._item,ls+
[node._item]
,res)
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