Insufficient Nodes in Root to Leaf Paths
<p>Given the <code>root</code> of a binary tree and an integer <code>limit</code>, delete all <strong>insufficient nodes</strong> in the tree simultaneously, and return <em>the root of the resulting binary tree</em>.</p>

<p>A node is <strong>insufficient</strong> if every root to <strong>leaf</strong> path intersecting this node has a sum strictly less than <code>limit</code>.</p>

<p>A <strong>leaf</strong> is a node with no children.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1000-1099/1080.Insufficient%20Nodes%20in%20Root%20to%20Leaf%20Paths/images/insufficient-11.png" style="width: 500px; height: 207px;" />
<pre>
<strong>Input:</strong> root = [1,2,3,4,-99,-99,7,8,9,-99,-99,12,13,-99,14], limit = 1
<strong>Output:</strong> [1,2,3,4,null,null,7,8,9,null,14]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1000-1099/1080.Insufficient%20Nodes%20in%20Root%20to%20Leaf%20Paths/images/insufficient-3.png" style="width: 400px; height: 274px;" />
<pre>
<strong>Input:</strong> root = [5,4,8,11,null,17,4,7,1,null,null,5,3], limit = 22
<strong>Output:</strong> [5,4,8,11,null,17,4,7,null,null,null,5]
</pre>

<p><strong class="example">Example 3:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/1000-1099/1080.Insufficient%20Nodes%20in%20Root%20to%20Leaf%20Paths/images/screen-shot-2019-06-11-at-83301-pm.png" style="width: 250px; height: 199px;" />
<pre>
<strong>Input:</strong> root = [1,2,-3,-5,null,4,null], limit = -1
<strong>Output:</strong> [1,null,-3,4]
</pre>

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

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 5000]</code>.</li>
	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>9</sup> &lt;= limit &lt;= 10<sup>9</sup></code></li>
</ul>
Tree; Depth-First Search; Binary Tree
/**
 * 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
 * @param {number} limit
 * @return {TreeNode}
 */
var sufficientSubset = function (root, limit) {
    if (root === null) {
        return null;
    }
    limit -= root.val;
    if (root.left === null && root.right === null) {
        return limit > 0 ? null : root;
    }
    root.left = sufficientSubset(root.left, limit);
    root.right = sufficientSubset(root.right, limit);
    return root.left === null && root.right === null ? null : root;
};
