原题链接:https://leetcode.com/problems/maximum-depth-of-binary-tree/description/
这道题目级别为“Easy”,也确实是简单!
不废话,直接使用递归实现深度优先搜索即可:
/**
* Created by clearbug on 2018/2/26.
*/
public class Solution {
static class TreeNode {
int val;
TreeNode left;
TreeNode right;
public TreeNode(int val) {
this.val = val;
}
}
public static void main(String[] args) {
TreeNode root = new TreeNode(1);
TreeNode rootLeft = new TreeNode(2);
TreeNode rootRight = new TreeNode(3);
root.left = rootLeft;
root.right = rootRight;
TreeNode leftLeft = new TreeNode(3);
TreeNode leftRight = null;
rootLeft.left = leftLeft;
rootLeft.right = leftRight;
TreeNode rightLeft = new TreeNode(2);
TreeNode rightRight = null;
rootRight.left = rightLeft;
rootRight.right = rightRight;
Solution s = new Solution();
System.out.println(s.maxDepth(root));
}
public int maxDepth(TreeNode root) {
if (root == null) {
return 0;
}
return dfs(root, 1);
}
public int dfs(TreeNode node, int currentDepth) {
int leftDepth = currentDepth, rightDepth = currentDepth;
if (node.left != null) {
leftDepth = dfs(node.left, currentDepth + 1);
}
if (node.right != null) {
rightDepth = dfs(node.right, currentDepth + 1);
}
return leftDepth > rightDepth ?
(leftDepth > currentDepth ? leftDepth : currentDepth) :
(rightDepth > currentDepth ? rightDepth : currentDepth);
}
}