LeetCode OJ--Binary Tree Level Order Traversal II

http://oj.leetcode.com/problems/binary-tree-level-order-traversal-ii/

树的层序遍历，和上一道题相比，对结果做一个顺序调整 reverse()

/**
* Definition for binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<vector<int> > levelOrderBottom(TreeNode *root) {
vector<vector<int> > ans;
if(root == NULL)
return ans;
int num = 1,num2 = 1,nullNum = 0,nullNumAcc = 0;
queue<TreeNode *> myQueue;
myQueue.push(root);
TreeNode *nodeFront;

vector<int> onePiece;
while(!myQueue.empty())
{
nodeFront = myQueue.front();
myQueue.pop();
num--;

onePiece.push_back(nodeFront->val);
if(nodeFront->left)
myQueue.push(nodeFront->left);
else
nullNum++;
if(nodeFront->right)
myQueue.push(nodeFront->right);
else
nullNum++;

if(num == 0)
{
if(onePiece.empty())
break;
ans.push_back(onePiece);
onePiece.clear();
num2 = num2*2;
nullNumAcc = nullNumAcc*2 + nullNum;
num = num2 - nullNumAcc;
nullNum = 0;
}
}
reverse(ans.begin(),ans.end());
return ans;
}
};