# Find Largest Value In Each Tree Row Problem

## Description

LeetCode Problem 515.

Given the root of a binary tree, return an array of the largest value in each row of the tree (0-indexed).

Example 1:

``````1
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Input: root = [1,3,2,5,3,null,9]
Output: [1,3,9]
``````

Example 2:

``````1
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Input: root = [1,2,3]
Output: [1,3]
``````

Example 3:

``````1
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Input: root = [1]
Output: [1]
``````

Example 4:

``````1
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Input: root = [1,null,2]
Output: [1,2]
``````

Example 5:

``````1
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Input: root = []
Output: []
``````

Constraints:

• The number of nodes in the tree will be in the range [0, 10^4].
• -2^31 <= Node.val <= 2^31 - 1

## Sample C++ Code

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/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode() : val(0), left(nullptr), right(nullptr) {}
*     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
*     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
vector<int> largestValues(TreeNode* root) {
vector<int> ans;
if (root == NULL)
return ans;

queue<TreeNode*> bfsQ;
bfsQ.push(root);

TreeNode* curr;
int len;
int max_node;

while (!bfsQ.empty()) {
len = bfsQ.size();
max_node = bfsQ.front()->val;

for (int i = 0; i < len; i ++) {
curr = bfsQ.front();
bfsQ.pop();

if (curr != NULL) {
if (curr->val > max_node)
max_node = curr->val;
if (curr->left != NULL)
bfsQ.push(curr->left);
if (curr->right != NULL)
bfsQ.push(curr->right);
}
}

ans.push_back(max_node);
}

return ans;
}
};
``````