给定一个二叉树,找出其最大深度。
二叉树的深度为根节点到最远叶子节点的最长路径上的节点数。
说明: 叶子节点是指没有子节点的节点

根据题意和之前的总结,本题也可以用两种算法去解决,一种迭代,一种递归,并且运行以后发现迭代的运行速度不如递归,
/**
* 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) {
//迭代算法
if(root==null) return 0;
Queue<TreeNode> queue=new LinkedList<>();
int ans=0;
queue.offer(root);
while(!queue.isEmpty()){
int len=queue.size();
ans++;
for(int i=0;i<len;i++){
TreeNode temtree=queue.poll();
if(temtree.left!=null) queue.offer(temtree.left);
if(temtree.right!=null) queue.offer(temtree.right);
}
}
return ans;
}
}
/**
* 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) {
return getDepth(root);
}
int getDepth(TreeNode root){
if(root==null)return 0;
int leftDepth=getDepth(root.left);
int rightDepth=getDepth(root.right);
int depth=1+Math.max(leftDepth,rightDepth);
return depth;
}
}
革命尚未成功,我仍需加倍努力
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