二叉树的深度（剑指offer）

/**
public 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) {
        int leftRoot=0;
        int rightRoot=0;
        if(root==null)  return 0;
        if(root.left!=null)
            leftRoot=TreeDepth(root.left);
        if(root.right!=null)
            rightRoot=TreeDepth(root.right);
        return Math.max(leftRoot,rightRoot)+1;
    }
}

public class Solution {
    public int TreeDepth(TreeNode root) {
        if(root==null) return 0;
        Queue<TreeNode> queue=new LinkedList<TreeNode>();
        queue.add(root);
        int count=0,depth=0,nextCount=1;
        while (!queue.isEmpty()){
            TreeNode top=queue.poll();
            count++;
            if(top.left!=null) queue.add(top.left);
            if(top.right!=null) queue.add(top.right);
            if(count==nextCount){
                nextCount=queue.size();
                depth++;
                count=0;
            }
        }
        return depth;
    }
}