Title
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.
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
Solution
这个我自己写的，ac，但又重复计算了，可以在f()中改的
//cpp:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int ans=0;
int f(TreeNode* t){
if(!t){
return 0;
}
return t->val+f(t->left)+f(t->right);
}
int findTilt(TreeNode* root) {
if(!root){
return 0;
}
return abs(f(root->left)-f(root->right))+findTilt(root->left)+findTilt(root->right);
}
};
这个是参考solution不重复计算的
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
int tilt=0;
public int findTilt(TreeNode root) {
traverse(root);
return tilt;
}
public int traverse(TreeNode root)
{
if(root==null )
return 0;
int left=traverse(root.left);
int right=traverse(root.right);
tilt+=Math.abs(left-right);
return left+right+root.val;
}
}