题解 | #牛牛的二叉树问题#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
#include <algorithm>
#include <unordered_map>
#include <utility>
#include <vector>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @param target double浮点型 
     * @param m int整型 
     * @return int整型vector
     */
    vector<int> findClosestElements(TreeNode* root, double target, int m) {
        unordered_map<TreeNode*,double> map;
        vector<int> ans;
        vector<pair<TreeNode*,double>> sta;
        auto foreach = [&](auto foreach,TreeNode* root,double target){
            if(root == nullptr){
                return;
            }
            map[root] = abs(root->val - target);
            foreach(foreach,root->left,target);
            foreach(foreach,root->right,target);
        };
        foreach(foreach,root,target);
        
        for(unordered_map<TreeNode*,double> :: iterator it = map.begin(); it != map.end(); it++){
            sta.emplace_back(pair<TreeNode*,double>(it->first,it->second));
        }
        sort(sta.begin(),sta.end(),[&](pair<TreeNode*,double> v1, pair<TreeNode*,double> v2) -> bool{
            return v1.second < v2.second;
        });
        for(int i = 0; i < m; i++){
            ans.emplace_back(sta[i].first->val);
        }
        sort(ans.begin(),ans.end());
        return ans;
    }
};