Given a binary tree with the following rules:
-
root.val == 0
- If
treeNode.val == x
andtreeNode.left != null
, thentreeNode.left.val == 2 * x + 1
- If
treeNode.val == x
andtreeNode.right != null
, thentreeNode.right.val == 2 * x + 2
Now the binary tree is contaminated, which means all treeNode.val
have been changed to -1
.
Implement the FindElements
class:
-
FindElements(TreeNode* root)
Initializes the object with a contaminated binary tree and recovers it. -
bool find(int target)
Returnstrue
if thetarget
value exists in the recovered binary tree.
Example 1:
Input
["FindElements","find","find"]
[[[-1,null,-1]],[1],[2]]
Output
[null,false,true]
Explanation
FindElements findElements = new FindElements([-1,null,-1]);
findElements.find(1); // return False
findElements.find(2); // return True
Example 2:
Input
["FindElements","find","find","find"]
[[[-1,-1,-1,-1,-1]],[1],[3],[5]]
Output
[null,true,true,false]
Explanation
FindElements findElements = new FindElements([-1,-1,-1,-1,-1]);
findElements.find(1); // return True
findElements.find(3); // return True
findElements.find(5); // return False
Example 3:
Input
["FindElements","find","find","find","find"]
[[[-1,null,-1,-1,null,-1]],[2],[3],[4],[5]]
Output
[null,true,false,false,true]
Explanation
FindElements findElements = new FindElements([-1,null,-1,-1,null,-1]);
findElements.find(2); // return True
findElements.find(3); // return False
findElements.find(4); // return False
findElements.find(5); // return True
Constraints:
-
TreeNode.val == -1
- The height of the binary tree is less than or equal to
20
- The total number of nodes is between
[1, 104]
- Total calls of
find()
is between[1, 104]
-
0 <= target <= 106
SOLUTION:
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class FindElements:
def __init__(self, root: Optional[TreeNode]):
self.root = root
self.exists = set()
nodes = [(self.root, 0)]
while len(nodes) > 0:
curr, l = nodes.pop()
if curr:
self.exists.add(l)
nodes.append((curr.left, 2 * l + 1))
nodes.append((curr.right, 2 * l + 2))
def find(self, target: int) -> bool:
return target in self.exists
# Your FindElements object will be instantiated and called as such:
# obj = FindElements(root)
# param_1 = obj.find(target)
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