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You are given the root
of a binary tree with n
nodes where each node
in the tree has node.val
coins. There are n
coins in total throughout the whole tree.
In one move, we may choose two adjacent nodes and move one coin from one node to another. A move may be from parent to child, or from child to parent.
Return the minimum number of moves required to make every node have exactly one coin.
Example 1:
Input: root = [3,0,0]
Output: 2
Explanation: From the root of the tree, we move one coin to its left child, and one coin to its right child.
Example 2:
Input: root = [0,3,0]
Output: 3
Explanation: 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.
Example 3:
Input: root = [1,0,2]
Output: 2
Example 4:
Input: root = [1,0,0,null,3]
Output: 4
Constraints:
- The number of nodes in the tree is
n
.
1 <= n <= 100
0 <= Node.val <= n
- The sum of all
Node.val
is n
.
[Tree]
[Depth-First Search]
[Binary Tree]
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