Given a binary tree, return the tilt of the whole tree.
The tilt of a tree node is defined as the absolute difference between the sum of all left subtree node values and the sum of all right subtree node values. Null node has tilt 0.
The tilt of the whole tree is defined as the sum of all nodes' tilt.
- The sum of node values in any subtree won't exceed the range of 32-bit integer.
- All the tilt values won't exceed the range of 32-bit integer.
Example:
- Input:
1
/
2 3
- Output: 1
- Explanation:
- Tilt of node 2 : 0
- Tilt of node 3 : 0
- Tilt of node 1 : |2-3| = 1
- Tilt of binary tree : 0 + 0 + 1 = 1
C Solution:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
int sum(struct TreeNode *root, int *res) {
if (!root) return 0;
int sum_left = sum(root->left, res);
int sum_right = sum(root->right, res);
*res += abs(sum_left - sum_right);
return root->val + sum_left + sum_right;
}
int findTilt(struct TreeNode* root) {
int res = 0;
sum(root, &res);
return res;
}
Python Solution:
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def findTilt(self, root):
"""
:type root: TreeNode
:rtype: int
"""
def traverse(root):
if not root: return 0, 0
l_sum, l_tilt = traverse(root.left)
r_sum, r_tilt = traverse(root.right)
return l_sum + r_sum + root.val, l_tilt + r_tilt + abs(l_sum - r_sum)
return traverse(root)[1]
Summary:
- nothing to say.
LeetCode: 563. Binary Tree Tilt
近期评论