leetcode.199二叉树的右视图

/**
 * 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) {
        TreeNode *p[10000],*q;
        vector<int> res;
        if(root==NULL){
            return res;
        }
        int rear=0,front=0,level=0,pos=0;
        p[rear++]=root;
        while(rear!=front){
            q=p[front++];
            if(q->left!=NULL){
                p[rear++]=q->left;
            }
            if(q->right!=NULL){
                p[rear++]=q->right;
            }
            if(front-1==pos){
                res.push_back(p[pos]->val);
                pos=rear-1;
                level++;
            }
        }
        return res;
    }
};