没想到都拖到2023年了 还没上500

471. Encode String with Shortest Length （Hard）

Given a string s, encode the string such that its encoded length is the shortest.

461. Hamming Distance (Easy)

The Hamming distance between two integers is the number of positions at which the corresponding bits are different.

451. Sort Characters By Frequency （Medium）

Given a string s, sort it in decreasing order based on the frequency of the characters. The frequency of a character is the number of times it appears in the string.

441. Arranging Coins （Easy）

You have n coins and you want to build a staircase with these coins. The staircase consists of k rows where the ith row has exactly i coins. The last row of the staircase may be incomplete.

431. Encode N-ary Tree to Binary Tree （Hard）

Design an algorithm to encode an N-ary tree into a binary tree and decode the binary tree to get the original N-ary tree. An N-ary tree is a rooted tree in which each node has no more than N children. Similarly, a binary tree is a rooted tree in which each node has no more than 2 children. There is no restriction on how your encode/decode algorithm should work. You just need to ensure that an N-ary tree can be encoded to a binary tree and this binary tree can be decoded to the original N-nary tree structure.

421. Maximum XOR of Two Numbers in an Array （Medium）

Given an integer array nums, return the maximum result of nums[i] XOR nums[j], where 0 <= i <= j < n.

411. Minimum Unique Word Abbreviation （Hard）

A string can be abbreviated by replacing any number of non-adjacent substrings with their lengths. For example, a string such as "substitution" could be abbreviated as (but not limited to):

中间搞laser project浪费了不少时间~~~

401. Binary Watch (Easy)

391. Perfect Rectangle （Hard）

Given an array rectangles where rectangles[i] = [xi, yi, ai, bi] represents an axis-aligned rectangle. The bottom-left point of the rectangle is (xi, yi) and the top-right point of it is (ai, bi).