Merge pull request #1148 from gowsp/patch-1

更新每个树行中找最大值Java实现

Author: youngyangyang04

problems/0102.二叉树的层序遍历.md

@@ -1287,23 +1287,23 @@ java代码：
 ```java
 class Solution {
     public List<Integer> largestValues(TreeNode root) {
-		List<Integer> retVal = new ArrayList<Integer>();
-		Queue<TreeNode> tmpQueue = new LinkedList<TreeNode>();
-		if (root != null) tmpQueue.add(root);
-		
-		while (tmpQueue.size() != 0){
-			int size = tmpQueue.size();
-			List<Integer> lvlVals = new ArrayList<Integer>();
-			for (int index = 0; index < size; index++){
-				TreeNode node = tmpQueue.poll();
-				lvlVals.add(node.val);
-				if (node.left != null) tmpQueue.add(node.left);
-				if (node.right != null) tmpQueue.add(node.right);
-			}
-			retVal.add(Collections.max(lvlVals));
-		}
-        
-        return retVal;
+        if(root == null){
+            return Collections.emptyList();
+        }
+        List<Integer> result = new ArrayList();
+        Queue<TreeNode> queue = new LinkedList();
+        queue.offer(root);
+        while(!queue.isEmpty()){
+            int max = Integer.MIN_VALUE;
+            for(int i = queue.size(); i > 0; i--){
+               TreeNode node = queue.poll();
+               max = Math.max(max, node.val);
+               if(node.left != null) queue.offer(node.left);
+               if(node.right != null) queue.offer(node.right);
+            }
+            result.add(max);
+        } 
+        return result;
     }
 }
 ```