python3 解法, 执行用时: 92 ms, 内存消耗: 19 MB, 提交时间: 2022-11-15 10:26:01

# 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 Solution:
    def sumEvenGrandparent(self, root: TreeNode) -> int:
        '''
        找到所有值为偶数的节点，并对这些节点的孙子节点（即子节点的子节点）统计答案
        '''
        q = collections.deque([root])
        ans = 0
        while len(q) > 0:
            node = q.popleft()
            if node.val % 2 == 0:
                if node.left:
                    if node.left.left:
                        ans += node.left.left.val
                    if node.left.right:
                        ans += node.left.right.val
                if node.right:
                    if node.right.left:
                        ans += node.right.left.val
                    if node.right.right:
                        ans += node.right.right.val
            if node.left:
                q.append(node.left)
            if node.right:
                q.append(node.right)
        return ans

python3 解法, 执行用时: 96 ms, 内存消耗: 19.2 MB, 提交时间: 2022-11-15 10:24:02

# 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 Solution:
    def sumEvenGrandparent(self, root: TreeNode) -> int:
        ans = 0

        def dfs(gp_val: int, p_val: int, node: TreeNode) -> None:
            '''
            gp_val: 祖父节点的值
            p_val: 父节点的值
            node: 当前节点
            '''
            if not node:
                return
            if gp_val % 2 == 0:
                nonlocal ans
                ans += node.val
            dfs(p_val, node.val, node.left)
            dfs(p_val, node.val, node.right)
        
        dfs(1, 1, root)
        return ans

python3 解法, 执行用时: 96 ms, 内存消耗: 19.3 MB, 提交时间: 2022-11-15 10:22:08

# 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 Solution:
    def sumEvenGrandparent(self, root: TreeNode) -> int:
        ans = 0

        def dfs(grandparent, parent, node):
            if not node:
                return
            if grandparent.val % 2 == 0:
                nonlocal ans
                ans += node.val
            dfs(parent, node, node.left)
            dfs(parent, node, node.right)
        
        if root.left:
            dfs(root, root.left, root.left.left)
            dfs(root, root.left, root.left.right)
        if root.right:
            dfs(root, root.right, root.right.left)
            dfs(root, root.right, root.right.right)
        
        return ans