distribute-coins-in-binary-tree.md

<p>Given the <code>root</code> of a binary tree with <code>N</code> nodes, each <code>node</code>&nbsp;in the tree has <code>node.val</code> coins, and there are <code>N</code> coins total.</p>

<p>In one move, we may choose two adjacent nodes and move one coin from one node to another.&nbsp; (The move may be from parent to child, or from child to parent.)</p>

<p>Return the number of moves required to make every node have exactly one coin.</p>

<p>&nbsp;</p>

<div>
<p><strong>Example 1:</strong></p>

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/01/18/tree1.png" style="width: 150px; height: 142px;" /></strong></p>

<pre>
<strong>Input: </strong><span id="example-input-1-1">[3,0,0]</span>
<strong>Output: </strong><span id="example-output-1">2</span>
<strong>Explanation: </strong>From the root of the tree, we move one coin to its left child, and one coin to its right child.
</pre>

<div>
<p><strong>Example 2:</strong></p>

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/01/18/tree2.png" style="width: 150px; height: 142px;" /></strong></p>

<pre>
<strong>Input: </strong><span id="example-input-2-1">[0,3,0]</span>
<strong>Output: </strong><span id="example-output-2">3</span>
<strong>Explanation: </strong>From the left child of the root, we move two coins to the root [taking two moves].  Then, we move one coin from the root of the tree to the right child.
</pre>

<div>
<p><strong>Example 3:</strong></p>

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/01/18/tree3.png" style="width: 150px; height: 142px;" /></strong></p>

<pre>
<strong>Input: </strong><span id="example-input-3-1">[1,0,2]</span>
<strong>Output: </strong><span id="example-output-3">2</span>
</pre>

<div>
<p><strong>Example 4:</strong></p>

<p><strong><img alt="" src="https://assets.leetcode.com/uploads/2019/01/18/tree4.png" style="width: 155px; height: 156px;" /></strong></p>

<pre>
<strong>Input: </strong><span id="example-input-4-1">[1,0,0,null,3]</span>
<strong>Output: </strong><span id="example-output-4">4</span>
</pre>

<p>&nbsp;</p>

<p><strong><span>Note:</span></strong></p>

<ol>
	<li><code>1&lt;= N &lt;= 100</code></li>
	<li><code>0 &lt;= node.val &lt;= N</code></li>
</ol>
</div>
</div>
</div>
</div>