Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
For example:
Given the following binary tree,
1 <---
/
2 3 <---
5 4 <---
You should return [1, 3, 4].
采用层序遍历的方式，每一层的最后一个结点即为在右侧可以看到的结点；
/**
* 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<int> rightSideView(TreeNode* root) {
queue<TreeNode*> nodes;
vector<int> vec;
vector< vector<int> > result;
vector<int> tmp;
if(NULL==root)
return vec;
nodes.push(root);
while(!nodes.empty())
{
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();
}
for(size_t i=0;i<result.size();++i)
{
vec.push_back(result[i][result[i].size()-1]);
}
return vec;
}
};