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  • leetCode(16):Binary Tree Level Order Traversal 分类: leetCode 2015-06-21 15:04 164人阅读 评论(0) 收藏

    Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).

    For example:
    Given binary tree {3,9,20,#,#,15,7},

        3
       / 
      9  20
        /  
       15   7
    

    return its level order traversal as:

    [
      [3],
      [9,20],
      [15,7]
    ]
    /**
     * Definition for a binary tree node.
     * struct TreeNode {
     *     int val;
     *     TreeNode *left;
     *     TreeNode *right;
     *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
     * };
     */
    class Solution {
    public:
        vector<vector<int>> levelOrder(TreeNode* root) {
            queue<TreeNode*> nodes;
        	vector< vector<int> > result;
        	vector<int> tmp;
        	if(NULL==root)
        		return result;
        	nodes.push(root);
        	while(!nodes.empty())
        	{//读取的同时,把下一层压入队列当中
        		int length=nodes.size();
        		int i=0;
        		while(i<length)
        		{
        			TreeNode* tmpNode=nodes.front();
        			tmp.push_back(tmpNode->val);
        			if(tmpNode->left)
        				nodes.push(tmpNode->left);
        			if(tmpNode->right)
        				nodes.push(tmpNode->right);
        			nodes.pop();
        			i++;
        		}
        		result.push_back(tmp);
        		tmp.clear();
        	}
        	return result;
        }
    };






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  • 原文地址:https://www.cnblogs.com/zclzqbx/p/4687099.html
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