标签：
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,null,null,15,7],
3
/ 9 20
/ 15 7
return its level order traversal as:
[ [3], [9,20], [15,7] ]
一层一层的输出
/**
* 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) {
vector<vector<int>> res;
if(root==NULL)return res;
queue<TreeNode*> q;
vector<int> temp;
q.push(root);
int curCount=1;
int nextCount=0;
while(!q.empty())
{
TreeNode* curNode=q.front();
temp.push_back(curNode->val);
q.pop();
curCount--;
if(curNode->left)
{
q.push(curNode->left);
nextCount++;
}
if(curNode->right)
{
q.push(curNode->right);
nextCount++;
}
if(curCount==0)
{
curCount=nextCount;
nextCount=0;
res.push_back(temp);
temp.clear();
}
}
return res;
}
};leetcode No102. Binary Tree Level Order Traversal
标签：
原文地址：http://blog.csdn.net/u011391629/article/details/52248567
