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@ -348,25 +348,29 @@ class Solution {
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```
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Python:
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0112.路径总和
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```python
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// 递归法
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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// 递归法
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class Solution:
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def hasPathSum(self, root: TreeNode, targetSum: int) -> bool:
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def isornot(root,targetSum)->bool:
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if (not root.left) and (not root.right) and targetSum == 0:return True // 遇到叶子节点,并且计数为0
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if (not root.left) and (not root.right):return False //遇到叶子节点,计数不为0
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if root.left:
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targetSum -= root.left.val //只有左节点
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if isornot(root.left,targetSum):return True //递归,处理节点
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targetSum -= root.left.val //左节点
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if isornot(root.left,targetSum):return True //递归,处理左节点
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targetSum += root.left.val //回溯
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if root.right:
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targetSum -= root.right.val //只有右节点
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targetSum -= root.right.val //右节点
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if isornot(root.right,targetSum):return True //递归,处理右节点
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targetSum += root.right.val //回溯
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return False
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@ -374,6 +378,46 @@ class Solution:
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if root == None:return False //别忘记处理空TreeNode
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else:return isornot(root,targetSum-root.val)
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```
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0113.路径总和-ii
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```python
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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//递归法
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class Solution:
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def pathSum(self, root: TreeNode, targetSum: int) -> List[List[int]]:
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path=[]
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res=[]
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def pathes(root,targetSum):
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if (not root.left) and (not root.right) and targetSum == 0: // 遇到叶子节点,并且计数为0
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res.append(path[:]) //找到一种路径,记录到res中,注意必须是path[:]而不是path
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return
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if (not root.left) and (not root.right):return // 遇到叶子节点直接返回
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if root.left: //左
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targetSum -= root.left.val
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path.append(root.left.val) //递归前记录节点
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pathes(root.left,targetSum) //递归
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targetSum += root.left.val //回溯
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path.pop() //回溯
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if root.right: //右
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targetSum -= root.right.val
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path.append(root.right.val) //递归前记录节点
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pathes(root.right,targetSum) //递归
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targetSum += root.right.val //回溯
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path.pop() //回溯
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return
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if root == None:return [] //处理空TreeNode
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else:
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path.append(root.val) //首先处理根节点
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pathes(root,targetSum-root.val)
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return res
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```
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Go:
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JavaScript:
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