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# Day 19: (Binary Tree)

[**Maximum path sum** ](https://leetcode.com/problems/binary-tree-maximum-path-sum/submissions/)\
Partially Solved on: Aug 5th 2020

```cpp
int helper(TreeNode* root, int res) {
    if (root==NULL) {
        return 0;
    }
    int ls = helper(root->left, res);
    int rs = helper(root->right, res);
    int max_single = max(max(ls, rs) + root->val, root->val);
    
    int max_top = max(max_single, ls+rs+root->val);
    
    res = max(max_single, max_top);
    
    return res;
}

int maxPathSum(TreeNode* root) {
    int res=INT_MIN;
    int ans = helper(root, res);
    
    return ans;
}    
```

[**Symmetric Tree**](https://leetcode.com/problems/symmetric-tree/)\
Solved on Aug 2nd 2020

```cpp
bool isSymmetric(TreeNode* root) {
        return isMirror(root, root);
}
    
bool isMirror(TreeNode* root1, TreeNode* root2) {
    if (root1 == NULL && root2 == NULL) {
        return true;
    }
    
    if (root1 && root2 && root1->val == root2->val) {
        return isMirror(root1->left, root2->right) && isMirror(root1->right, root2->left);        
    }
    return false;
}
```