Leetcode 2021-04-13
🟢 783.minimum-distance-between-bst-nodes
#tree #depth-first-search #recursion

Given the root of a Binary Search Tree (BST), return the minimum difference between the values of any two different nodes in the tree.

Input: root = [4,2,6,1,3]
Output: 1

Leetcode 2021-04-14
🟡 208.implement-trie-prefix-tree
#design #trie

A trie (pronounced as "try") or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.

Input
["Trie", "insert", "search", "search", "startsWith", "insert", "search"]
[[], ["apple"], ["apple"], ["app"], ["app"], ["app"], ["app"]]
Output
[null, null, true, false, true, null, true]

Explanation
Trie trie = new Trie();
trie.insert("apple");
trie.search("apple");   // return True
trie.search("app");     // return False
trie.startsWith("app"); // return True
trie.insert("app");
trie.search("app");     // return True

Leetcode 2021-04-15
🟡 213.house-robber-ii
#dynamic-programming

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, adjacent houses have a security system connected, and it will automatically contact the police if two adjacent houses were broken into on the same night.

Input: nums = [2,3,2]
Output: 3
Explanation: You cannot rob house 1 (money = 2) and then rob house 3 (money = 2), because they are adjacent houses.