public class Solution {
    //真是个莫名其妙的的题目
    //Runtime: 3 ms, faster than 100.00% 
    //Memory Usage: 40.8 MB, less than 10.53%
    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;
    }
}