[LeetCode] 199 - Binary Tree Right Side View

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].

 

/**
* 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) {
    vector<int> res;
    if (root == nullptr) {
      return res;
    }
    queue<TreeNode*> nodeQueue;
    nodeQueue.emplace(root);
    while (!nodeQueue.empty()) {
      int num = nodeQueue.size();
      TreeNode *n;
      for (int i = 0 ; i < num; ++i) {
        n = nodeQueue.front();
        nodeQueue.pop();
        if (n->left) {
          nodeQueue.emplace(n->left);
        }
        if (n->right) {
          nodeQueue.emplace(n->right);
        }
      }
      res.emplace_back(n->val);
    }
    return res;
  }
};

 

posted on 2015-08-28 11:41  tuituji  阅读(119)  评论(0编辑  收藏  举报

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