Add to List 563. Binary Tree Tilt

最新推荐文章于 2020-11-25 20:39:50 发布

原创最新推荐文章于 2020-11-25 20:39:50 发布 · 537 阅读

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本文介绍了一种通过递归计算二叉树每个节点的倾斜值并求和的方法。倾斜值定义为左子树节点值之和与右子树节点值之和的绝对差。文章提供了一个具体的例子和实现代码。

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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:
1o
/ \
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
这道题也是递归的方法去做。从底部算出tilt后，继续往上，然后相加起来
代码如下：

/**
 * 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 sum=0;
    int findTilt(TreeNode* root) {
        help(root);
        return sum;
    }
    int help(TreeNode* root){
        if(root==NULL)return 0;
        int left=help(root->left);
        int right=help(root->right);
        sum+=abs(left-right);
        return root->val+left+right;
    }
};