《LeetCode力扣练习》代码随想录——二叉树（二叉搜索树中的众数---Java）

《LeetCode力扣练习》代码随想录——二叉树（二叉搜索树中的众数—Java）

刷题思路来源于 代码随想录

501. 二叉搜索树中的众数

• 二叉树-中序遍历

  /**
   * Definition for a binary tree node.
   * public class TreeNode {
   * int val;
   * TreeNode left;
   * TreeNode right;
   * TreeNode() {}
   * TreeNode(int val) { this.val = val; }
   * TreeNode(int val, TreeNode left, TreeNode right) {
   * this.val = val;
   * this.left = left;
   * this.right = right;
   * }
   * }
   */
  class Solution {
  
      private TreeNode pre = null;
      private int count = 0;
      private int maxCount = 0;
      private List<Integer> result = new ArrayList<>();
  
      public int[] findMode(TreeNode root) {
  
          recursion(root);
  
          int[] nums = new int[result.size()];
          for (int i = 0; i < result.size(); i++) {
              nums[i] = result.get(i);
          }
  
          return nums;
  
      }
  
      private void recursion(TreeNode root) {
  
          if (root == null) {
              return;
          }
  
          recursion(root.left);
  
          if (pre == null) {
              count = 1;
          } else if (pre != null && root.val == pre.val) {
              count++;
          } else {
              count = 1;
          }
  
          if (count == maxCount) {
              result.add(root.val);
          }
  
          if (count > maxCount) {
              maxCount = count;
              result = new ArrayList<>();
              result.add(root.val);
          }
  
          pre = root;
  
          recursion(root.right);
  
          return;
  
      }
  }
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