亚麻：max sbustree

这是亚麻的OA 题

这里的代码没有经过测试

Given a binary tree, find the subtree with maximum sum. Return the root of the subtree.

 

another similar problem in leetcode :

https://leetcode.com/problems/most-frequent-subtree-sum/description/

which has passed all the testcases.

// key point 
// use recursive
// use maxval and node to record the point meet the requirement . can also use pair( maxval , node ) to recorde the max value point.

struct TreeNode {
    TreeNode* right = null;
    TreeNode* left =null ;
    int val  =0;
}

int  _MaxSubtree ( TreeNode* root , TreeNode* & res , int maxvalue){

    if ( root == null  ) return 0;

    int vall = _MaxSubtree( root.left , res, maxvalue);
     int valr  =_MaxSubtree (root.right, res. maxvalue);
    
    int val = root.val + vall + valr;
    if ( val > res ){
        res = root;
        maxvalue = val; 
    }

    return val;

    }
}

TreeNode * MaxSubtree ( TreeNode* root ){
    if (root == null ) return null;

    TreeNode* res == null;
    int maxval = INT_MIN;

    _ MaxSubtree( root, res, maxval);

    return res;
}