题解 | #二叉树的深度#

/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
import java.util.*;
public class Solution {
    public int TreeDepth(TreeNode root) {
        if(root==null) return 0;
        int left = TreeDepth(root.left);
        int right = TreeDepth(root.right);
        return 1+Math.max(left,right);
        //return helper(root);
    }
    /**** 层序遍历 时间O(N)空间O(N) *****/
    public int helper(TreeNode root){
        if(root==null) return 0;
        Queue<TreeNode> q = new LinkedList<>();
        q.add(root);
        int high = 0;
        while(!q.isEmpty()){
            int size = q.size();
            for(int i=0;i<size;i++){
                TreeNode cur = q.poll();
                if(cur.left!=null){
                    q.add(cur.left);
                }
                if(cur.right!=null){
                    q.add(cur.right);
                }
            }
            high++;
        }
        return high;
    }
    /**********************************/
}