技術標籤：LeetCodeleetcode二叉樹DFS/BFSjava

一、題目

演示示例：

二、測試程式碼

//方法一 遞迴(DFS)
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
 

class Solution {
    public int maxDepth(TreeNode root) {
        if(root==null){
            return 0;
        }
        int leftDepth=maxDepth(root.left);
        int rightDepth=maxDepth(root.right);
    return Math.max(leftDepth,rightDepth)+1;
    }
}

//方法二 非遞迴(BFS)
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
 

class Solution {
    public int maxDepth(TreeNode root) {
        if(root==null) {
			return 0;
		}
		Queue<TreeNode> queue=new LinkedList<>();
		queue.offer(root);
		int res=0;
		while(!queue.isEmpty()) {
			int size=queue.size();
			while(size>0) {
				TreeNode temp=queue.poll();
				if
 
(temp.left!=null) {
					queue.offer(temp.left);
				}
				if(temp.right!=null) {
					queue.offer(temp.right);
				}
				size--;
			}
			res++;
		}
    return res;
    }
}

三、執行情況

方法一：

方法二：

傳送門：二叉樹最大深度(高度)/結點個數 / 葉子結點個數 / 第k層結點個數的求解