LeetCode: Diameter of Binary Tree

LeetCode: Diameter of Binary Tree

Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.

Example:

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Given a binary tree
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/ \
2 3
/ \
4 5
Return 3, which is the length of the path [4,2,1,3] or [5,2,1,3].

Note: The length of path between two nodes is represented by the number of edges between them.

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/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public int diameterOfBinaryTree(TreeNode root) {
if (root == null) return 0;

Queue<TreeNode> queue = new LinkedList<>();
queue.add(root);
int result = 0;
while (!queue.isEmpty()) {
TreeNode node = queue.poll();
result = Math.max(result, getMaxDepth(node.left) + getMaxDepth(node.right));
if (node.left != null) queue.add(node.left);
if (node.right != null) queue.add(node.right);
}
return result;
}

private int getMaxDepth(TreeNode node) {
if (node == null) {
return 0;
}
return Math.max(getMaxDepth(node.left), getMaxDepth(node.right)) + 1;
}
}