Deepest Leaves Sum
Given the <code>root</code> of a binary tree, return <em>the sum of values of its deepest leaves</em>.

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1300-1399/1302.Deepest%20Leaves%20Sum/images/1483_ex1.png" style="width: 273px; height: 265px;" />
<pre>
<strong>Input:</strong> root = [1,2,3,4,5,null,6,7,null,null,null,null,8]
<strong>Output:</strong> 15
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
<strong>Output:</strong> 19
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 10<sup>4</sup>]</code>.</li>
	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
</ul>
Tree; Depth-First Search; Breadth-First Search; Binary Tree
/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func deepestLeavesSum(root *TreeNode) (ans int) {
	q := []*TreeNode{root}
	for len(q) > 0 {
		ans = 0
		for k := len(q); k > 0; k-- {
			node := q[0]
			q = q[1:]
			ans += node.Val
			if node.Left != nil {
				q = append(q, node.Left)
			}
			if node.Right != nil {
				q = append(q, node.Right)
			}
		}
	}
	return
}
