Problem
Given the root of a binary tree, return an array of the largest value in each row of the tree (0-indexed).
Example 1:
Input: root = [1,3,2,5,3,null,9]
Output: [1,3,9]
Example 2:
Input: root = [1,2,3]
Output: [1,3]
Constraints:
The number of nodes in the tree will be in the range
[0, 104].-231 <= Node.val <= 231 - 1
Solution
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @return {number[]}
*/
var largestValues = function(root) {
var res = [];
dfs(root, 0, res);
return res;
};
var dfs = function(root, row, res) {
if (!root) return;
res[row] = Math.max(
res[row] === undefined ? Number.MIN_SAFE_INTEGER : res[row],
root.val,
);
dfs(root.left, row + 1, res);
dfs(root.right, row + 1, res);
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).