501.cpp

// inOrderTraversal.cpp
/**
 * 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> result;
  int curCount = 0;
  int maxCount = 0;
  int lastValue;
  bool firstTime = 1;

public:
  vector<int> findMode(TreeNode *root) {
    inOrder(root);
    return result;
  }
  void inOrder(TreeNode *root) {
    if (root == NULL)
      return;
    inOrder(root->left);
    if (firstTime) {
      lastValue = root->val;
      firstTime = 0;
    }
    if (lastValue != root->val) {
      curCount = 0;
      lastValue = root->val;
    }
    if (lastValue == root->val) {
      ++curCount;
      if (curCount == maxCount) {
        result.push_back(lastValue);
      } else if (curCount > maxCount) {
        maxCount = curCount;
        result.clear();
        result.push_back(lastValue);
      }
    }
    inOrder(root->right);
  }
};