Create 501-find-mode-in-binary-search-tree.js

Author: everthis

501-find-mode-in-binary-search-tree.js

@@ -0,0 +1,30 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number[]}
+ */
+const findMode = function(root) {
+  if(root == null) return []
+  const hash = {}
+  traverse(root, hash)
+  const res = Object.entries(hash).sort((a, b) => b[1] - a[1])
+  const result = [res[0][0]]
+  for(let i = 1; i < res.length; i++) {
+    if(res[i][1] === res[0][1]) result.push(res[i][0])
+    else break
+  }
+  return result
+};
+
+function traverse(node, hash) {
+  if(node === null) return
+  hash[node.val] = Object.prototype.hasOwnProperty.call(hash, node.val) ? hash[node.val] + 1 : 1
+  traverse(node.left, hash)
+  traverse(node.right, hash)
+}