剑指Offer—38—二叉树的深度

package A38二叉树的最大深度;

import java.util.LinkedList;
import java.util.Queue;

public class Demo {

public int TreeDepth(TreeNode pRoot){
if (pRoot == null){
return 0;
}

Queue<TreeNode> queue = new LinkedList<>();
queue.add(pRoot);
int depth = 0;
while (!queue.isEmpty()){
depth++;
int size = queue.size();
while (size-- > 0){
TreeNode temp = queue.poll();
if (temp.left != null){
queue.add(temp.left);
}
if (temp.right != null){
queue.add(temp.right);
}
}
}
return depth;
}
}

package A38二叉树的最大深度;
class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;

public TreeNode(int val) {
this.val = val;
}
}
public class Solution {
public int TreeDepth(TreeNode root) {
if (root == null){
return 0;
}
int left = TreeDepth(root.left);
int right = TreeDepth(root.right);
return (left > right) ? (left + 1) : (right + 1);
}
}

package A38二叉树的最大深度;

import java.util.LinkedList;
import java.util.Queue;

public class Solution1 {
// 层次遍历

public int TreeDepth(TreeNode pRoot){
if (pRoot == null){
return 0;
}
Queue<TreeNode> queue = new LinkedList<>();
queue.add(pRoot);
int depth = 0;
while (!queue.isEmpty()){
int len = queue.size();
depth++;
while (len-- > 0) {  // 把队列中的元素吐完
TreeNode top = queue.poll();
if (top.left != null) {
queue.add(top.left);
}
if (top.right != null) {
queue.add(top.right);
}
}
}
return depth;
}
}