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_0104_MaximumDepthOfBinaryTree.java
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_0104_MaximumDepthOfBinaryTree.java
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package com.diguage.algorithm.leetcode;
import com.diguage.algorithm.util.TreeNode;
import java.util.Arrays;
import java.util.Objects;
import static com.diguage.algorithm.util.TreeNodeUtils.buildTree;
/**
* = 104. Maximum Depth of Binary Tree
*
* https://leetcode.com/problems/maximum-depth-of-binary-tree/[Maximum Depth of Binary Tree - LeetCode]
*
* Given a binary tree, find its maximum depth.
*
* The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
*
* *Note:* A leaf is a node with no children.
*
* *Example:*
*
* Given binary tree `[3,9,20,null,null,15,7]`,
*
* ----
* 3
* / \
* 9 20
* / \
* 15 7
* ----
*
* return its depth = 3.
*
* @author D瓜哥, https://www.diguage.com/
* @since 2020-01-24 22:17
*/
public class _0104_MaximumDepthOfBinaryTree {
/**
* Runtime: 1 ms, faster than 14.28% of Java online submissions for Maximum Depth of Binary Tree.
*
* Memory Usage: 40.7 MB, less than 5.38% of Java online submissions for Maximum Depth of Binary Tree.
*/
public int maxDepth(TreeNode root) {
if (Objects.isNull(root)) {
return 0;
}
int left = 0;
if (Objects.nonNull(root.left)) {
left = maxDepth(root.left);
}
int right = 0;
if (Objects.nonNull(root.right)) {
right = maxDepth(root.right);
}
return Math.max(left, right) + 1;
}
public static void main(String[] args) {
_0104_MaximumDepthOfBinaryTree solution = new _0104_MaximumDepthOfBinaryTree();
int r1 = solution.maxDepth(buildTree(Arrays.asList(3, 9, 20, null, null, 15, 7)));
System.out.println((r1 == 3) + " : " + r1);
}
}