二叉树层序遍历

 1 void LevelOrder(TreeNode* root,vector<int>& res){
 2     if(!root) return;
 3     queue<TreeNode*> q;
 4     TreeNode* node;
 5     q.push(root);
 6     while(!q.empty()){
 7         node=q.front();
 8         q.pop();
 9         res.push_back(node->value);
10         if(node->left)   q.push(node->left);
11         if(node->right)  q.push(node->right);  
12         
13      }
14 }