Leetcode 501 Solution

This article provides solution to leetcode question 501 (find-mode-in-binary-search-tree)
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https://leetcode.com/problems/find-mode-in-binary-search-tree

Solution

/**
 * 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 {
    vector<int> res;
    int curr_cnt = 0;
    int max_cnt = 0;

public:
    void findMode(TreeNode* root, int& prev) {
        if (root == NULL)
            return;

        findMode(root->left, prev);

        if (max_cnt != 0 && prev == root->val)
            curr_cnt++;
        else
        {
            prev = root->val;
            curr_cnt = 1;
        }

        if (curr_cnt > max_cnt)
        {
            max_cnt = curr_cnt;
            res.clear();
            res.push_back(root->val);
        }
        else if (curr_cnt == max_cnt)
            res.push_back(root->val);

        findMode(root->right, prev);
    }

    vector<int> findMode(TreeNode* root) {
        int prev = INT_MAX;
        findMode(root, prev);
        return res;
    }
};