Leetcode Binary Tree Right Side View

/**
* Definition for binary tree
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class Solution {
public List<Integer> rightSideView(TreeNode root) {
Map<Integer,Integer> map = new HashMap<Integer,Integer>();
breadthFirstSearch(root,map,0);

List<Integer> list = new LinkedList<Integer>();

for(Entry<Integer,Integer> entry:map.entrySet()){
list.add(entry.getKey(),entry.getValue());
}

return list;
}

public void breadthFirstSearch(TreeNode root,Map<Integer,Integer> map,int depth){
if(root == null){
return;
}

if(!map.containsKey(depth)){
map.put(depth,root.val);
}

breadthFirstSearch(root.right,map,depth+1);
breadthFirstSearch(root.left,map,depth+1);
}
}

/**
* Definition for binary tree
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class Solution {
public List<Integer> rightSideView(TreeNode root) {

List<Integer> list = new LinkedList<Integer>();
Queue<TreeNode> queue = new LinkedList<TreeNode>();
int count = 0;
count++;
if(root == null){
return list;
}
queue.offer(root);

while(true){
int next = 0;
while(count>0){
TreeNode tmp = queue.poll();
count--;
if(count == 0){
list.add(tmp.val);
}

if(tmp.left != null){
queue.offer(tmp.left);
next++;
}

if(tmp.right != null){
queue.offer(tmp.right);
next++;
}
}

if(next==0){
break;
}else{
count = next;
}
}

return list;
}
}