二叉树的层次遍历 II -LintCode

#ifndef C70_H
#define C70_H
#include<iostream>
#include<vector>
#include<queue>
#include<stack>
#include<algorithm>
using namespace std;
class TreeNode{
public:
int val;
TreeNode *left, *right;
TreeNode(int val){
this->val = val;
this->left = this->right = NULL;
}
};
class Solution {
public:
/*
* @param root: A tree
* @return: buttom-up level order a list of lists of integer
*/
vector<vector<int>> levelOrderBottom(TreeNode * root) {
// write your code here
vector<vector<int>> res;
if (!root)
return res;
queue<TreeNode*> que;
que.push(root);
//类似于层次遍历
while (!que.empty())
{
int size = que.size();
vector<int> vec;
for (int i = 0; i < size; ++i)
{
TreeNode *node = que.front();
que.pop();
vec.push_back(node->val);
if (node->left)
que.push(node->left);
if (node->right)
que.push(node->right);
}
res.push_back(vec);
}
//反转容器内容
reverse(res.begin(), res.end());
return res;
}
};
#endif