程序在Python中查找具有偶数和的最长路径的长度
假设我们有一棵二叉树。我们必须找到总和为偶数的最长路径的长度。
因此，如果输入像图像，那么输出将是5，因为路径像[5、2、4、8、5]，总和=24(even)。
范例(Python)
让我们看下面的实现以更好地理解-
class TreeNode:
def __init__(self, data, left = None, right = None):
self.val = data
self.left = left
self.right = right
class Solution:
def solve(self, root):
def dfs(node):
if not node:
return 0, float("-inf")
left_0, left_1 = dfs(node.left)
right_0, right_1 = dfs(node.right)
if node.val & 1:
self.ans = max(self.ans, left_1 + right_0 + 1, left_0 + right_1 + 1)
return max(left_1 + 1, right_1 + 1, 0), max(left_0 + 1, right_0 + 1)
else:
self.ans = max(self.ans, left_0 + right_0 + 1, left_1 + right_1 + 1)
return max(left_0 + 1, right_0 + 1, 0), max(left_1 + 1, right_1 + 1)
self.ans = 0
dfs(root)
return self.ans
ob = Solution()
root = TreeNode(2)
root.left = TreeNode(5)
root.right = TreeNode(4)
root.right.left = TreeNode(8)
root.right.right = TreeNode(2)
root.right.left.left = TreeNode(5)
print(ob.solve(root))输入值
root = TreeNode(2) root.left = TreeNode(5) root.right = TreeNode(4) root.right.left = TreeNode(8) root.right.right = TreeNode(2) root.right.left.left = TreeNode(5)输出结果
5
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