solves mode in bst

Author: anishLearnsToCode

Diff for: README.md

@@ -1,8 +1,8 @@
 # LeetCode Algorithms
 
-![problems-solved](https://img.shields.io/badge/Problems%20Solved-108/571-1f425f.svg)
-![problems-solved-java](https://img.shields.io/badge/Java-108/1571-1abc9c.svg)
-![problems-solved-python](https://img.shields.io/badge/Python-108/1571-1abc9c.svg)
+![problems-solved](https://img.shields.io/badge/Problems%20Solved-109/571-1f425f.svg)
+![problems-solved-java](https://img.shields.io/badge/Java-109/1571-1abc9c.svg)
+![problems-solved-python](https://img.shields.io/badge/Python-109/1571-1abc9c.svg)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 
 🔒 = Subscription Content
@@ -132,7 +132,7 @@
 | 492 | [Construct the Rectangle](https://leetcode.com/problems/construct-the-rectangle) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/ConstructTheRectangle.java) [![Python](https://img.icons8.com/color/35/000000/python.png)](python/construct_the_rectangle.py) |
 | 496 | [Next Greater Element I](https://leetcode.com/problems/next-greater-element-i) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/NextGreaterElementI.java) [![Python](https://img.icons8.com/color/35/000000/python.png)](python/next_greater_element_i.py) |
 | 500 | [Keyboard Row](https://leetcode.com/problems/keyboard-row) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/KeyBoardRow.java) [![Python](https://img.icons8.com/color/35/000000/python.png)](python/keyboard_row.py) |
-| 501 | [Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree) | Easy | |
+| 501 | [Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/FindModeInBinarySearchTree) [![Python](https://img.icons8.com/color/35/000000/python.png)](python/find_mode_in_binary_search_tree.py) |
 | 504 | [Base 7](https://leetcode.com/problems/base-7) | Easy | |
 | 506 | [Relative Ranks](https://leetcode.com/problems/relative-ranks) | Easy | |
 | 507 | [Perfect Number](https://leetcode.com/problems/perfect-number) | Easy | |

Diff for: python/find_mode_in_binary_search_tree.py

@@ -0,0 +1,37 @@
+# Definition for a binary tree node.
+from typing import List
+
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
+class Solution:
+    def __init__(self):
+        self.count = 1
+        self.previous = None
+        self.max = 0
+
+    def find_mode(self, root: TreeNode, modes: List[int]):
+        if root is None:
+            return
+        self.find_mode(root.left, modes)
+        if self.previous:
+            self.count = self.count + 1 if root.val == self.previous.val else 1
+        if self.count > self.max:
+            self.max = self.count
+            modes.clear()
+            modes.append(root.val)
+        elif self.count == self.max:
+            modes.append(root.val)
+        self.previous = root
+        self.find_mode(root.right, modes)
+
+    def findMode(self, root: TreeNode) -> List[int]:
+        if root is None: return []
+        result = []
+        self.find_mode(root, result)
+        return result

Diff for: src/FindModeInBinarySearchTree.java

@@ -1,3 +1,63 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
 public class FindModeInBinarySearchTree {
-    
+    static 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;
+        }
+    }
+
+    private static TreeNode previous;
+    private static int count = 1;
+    private static int mode = 0;
+
+    public static int[] findMode(TreeNode root) {
+        if (root == null) {
+            return new int[0];
+        }
+
+        List<Integer> modes = new ArrayList<>();
+        findMode(root, modes);
+        int[] result = new int[modes.size()];
+        for(int index = 0 ; index < modes.size() ; index++) {
+            result[index] = modes.get(index);
+        }
+        previous = null;
+        count = 1;
+        mode = 0;
+        return result;
+    }
+
+    private static void findMode(TreeNode root, List<Integer> modes) {
+        if (root == null) {
+            return;
+        }
+        findMode(root.left, modes);
+        if (previous != null) {
+            count = root.val == previous.val ? count + 1 : 1;
+        }
+        if (count > mode) {
+            mode = count;
+            modes.clear();
+            modes.add(root.val);
+        } else if (count == mode) {
+            modes.add(root.val);
+        }
+        previous = root;
+        findMode(root.right, modes);
+    }
+
+    public static void main(String[] args) {
+        TreeNode root = new TreeNode(0);
+        System.out.println(Arrays.toString(findMode(root)));
+    }
 }