[leetcode]199. Binary Tree Right Side View

Analysis

好冷鴨—— [每天刷題並不難0.0]

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.

層序遍歷二叉樹，然後輸出每層最右邊的節點值

Implement

/**
 * 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)
            return
 
 res;
        queue<TreeNode*> q;
        q.push(root);
        while(!q.empty()){
            int len = q.size();
            for(int i=0; i<len; i++){
                TreeNode* node = q.front();
                q.pop();
                if(i == len-1)
                    res.push_back(node-
 
>val);
                if(node->left)
                    q.push(node->left);
                if(node->right)
                    q.push(node->right);
            }
        }
        return res;
    }

};