[leetcode] 199. Binary Tree Right Side View

Binary Tree Right Side View

描述

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,

You should return [1, 3, 4]

我的代碼

可以廣搜也可以深搜：
深搜代碼：

/**
 * 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> rlt;
        dfs(root, 1, rlt);
        return rlt;
    }
private:
    void dfs(TreeNode* root, int step, vector<int>& vec)
    {
        if (!root) return;
        if (vec.size()<step) vec.push_back(root->val);
        dfs(root->right, step+1, vec);
        dfs(root->left, step+1, vec);
    }
};

廣搜代碼：

 */
class Solution {
public:
    vector<int> rightSideView(TreeNode* root) {
        queue<TreeNode*> q;
        vector<int> rlt;
        if (root)
        {
            q.push(root);
            while(!q.empty())
            {
                rlt.push_back(q.front()->val);
                int _size=q.size();
                while(_size)
                {
                    TreeNode* tmp=q.front();
                    q.pop();
                    if (tmp->right) q.push(tmp->right);
                    if (tmp->left) q.push(tmp->left);
                    _size--;
                }
            }
        }
        return rlt;
    }
};