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题目：

You need to find the largest value in each row of a binary tree.

Example:

Input:           1         / \        3   2       / \   \        5   3   9 Output: [1, 3, 9]

解释：

# Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    def largestValues(self, root):        """        :type root: TreeNode        :rtype: List[int]        """        result=[]        if not root:            return result        queue=[root]        while queue:            layer_number=len(queue)            temp_max=float('-inf')            for i in xrange(layer_number):                tmp=queue.pop(0)                if tmp.left:                    queue.append(tmp.left)                if tmp.right:                    queue.append(tmp.right)                temp_max=max(temp_max,tmp.val)            result.append(temp_max)        return result

c++代码：

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */#include
   
    using namespace std;class Solution {
   public:    vector
    
      largestValues(TreeNode* root) {
           vector
     
      result;        if(!root)            return result;        queue
      
       _queue;        _queue.push(root);        while (!_queue.empty())        {
               int len_layer=_queue.size();            int max_val=INT_MIN;            for (int i=0;i
       
        left)                    _queue.push(tmp->left);                if(tmp->right)                    _queue.push(tmp->right);                max_val=max(max_val,tmp->val);             }            result.push_back(max_val);        }        return result;     }};
       
      
     
    
   

总结：

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