Distribute Coins in Binary Tree - Problem
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.
Input & Output
Example 1 — Basic Imbalanced Tree
$
Input:
root = [3,0,0]
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Output:
2
💡 Note:
Root has 3 coins, both children have 0. Move 1 coin from root to each child: root→left (1 move), root→right (1 move). Total: 2 moves.
Example 2 — Already Balanced
$
Input:
root = [1,1,1]
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Output:
0
💡 Note:
Each node already has exactly 1 coin. No moves needed.
Example 3 — Complex Distribution
$
Input:
root = [1,0,2]
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Output:
2
💡 Note:
Left child needs 1 coin, right child has 1 extra. Move 1 coin from right to root (1 move), then from root to left (1 move). Total: 2 moves.
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.
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Explanation
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