具体思路：

和之前一道题思路相同；

具体思路：

/**
 * 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<vector<int>> verticalTraversal(TreeNode* root) {
        vector<vector<int>> ret;
        if(!root)
            return ret;
        queue<pair<TreeNode*,int>> q;
        map<int,vector<int>>mp;
        q.push({root,0});
        while(!q.empty()){
            int size=q.size();
            map<int,vector<int>>temp;
            while(size!=0){
                size--;
                auto pa=q.front();
                q.pop();
                temp[pa.second].push_back(pa.first->val);
                if(pa.first->left){
                    q.push({pa.first->left,pa.second-1});
                }
                if(pa.first->right){
                    q.push({pa.first->right,pa.second+1});
                }
            }
            for(auto it=temp.begin();it!=temp.end();it++){
                sort(it->second.begin(),it->second.end());
                mp[it->first].insert(mp[it->first].end(),it->second.begin(),it->second.end());
            }
        }
        for(auto it=mp.begin();it!=mp.end();it++){
            //sort(it->second.begin(),it->second.end());
            ret.push_back(it->second);
        }
        return ret;
    }
};