leetcode 199.二叉树的右视图

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<int> rightSideView(TreeNode* root) {
        queue<TreeNode*> q;
        vector<int> res;
        if(root!=NULL) q.push(root);
        while(!q.empty()){
            int len=q.size();

            for(int i=0;i<len;i++){
                TreeNode* cur=q.front();
                q.pop();

                if(i==(len-1)){
                    int curN=cur->val;
                    res.push_back(curN);
                }

                if(cur->left!=NULL) q.push(cur->left);
                if(cur->right!=NULL) q.push(cur->right);

            }



        }
        return res; 
    }
};

层序遍历简单调整