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 <cmath>
#include <queue>
#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) {
        vector<int> res = {};

        if (root == nullptr) {
            return res;
        }

        queue<TreeNode*> que;
        TreeNode* cur;
        que.push(root);

        while (!que.empty()) {
            cur = que.front();
            res.push_back(cur->val);
            que.pop();
            if (cur->left != nullptr) {
                que.push(cur->left);
            }
            if (cur->right != nullptr) {
                que.push(cur->right);
            }
        }

        sort(res.begin(), res.end());
        vector<int> result;

        for (auto num : res) {
            if (result.size() < m) {
                result.push_back(num);
            } else {
                double max_diff = fabs(result.front() - target);
                int max_index = 0;
                for (int i = 1; i < m; i++) {
                    double diff = fabs(result[i] - target);
                    if (diff > max_diff) {
                        max_diff = diff;
                        max_index = i;
                    }
                }
                if (fabs(num - target) < max_diff) {
                    result[max_index] = num;
                }
            }
        }
        sort(result.begin(), result.end());
        return result;
    }
};