401 
Binary Watch 
Easy 

402 
Remove K Digits 
Medium 

403 
Frog Jump 
Hard 

404 
Sum of Left Leaves 
Easy 
Tree

405 
Convert a Number to Hexadecimal 
Easy 

406 
Queue Reconstruction by Height 
Medium 

407 
Trapping Rain Water II 
Hard 

409 
Longest Palindrome 
Easy 

410 
Split Array Largest Sum 
Hard 

412 
Fizz Buzz 
Easy 

413 
Arithmetic Slices 
Medium 

414 
Third Maximum Number 
Easy 

415 
Add Strings 
Easy 

416 
Partition Equal Subset Sum 
Medium 

417 
Pacific Atlantic Water Flow 
Medium 

419 
Battleships in a Board 
Medium 

420 
Strong Password Checker 
Hard 

421 
Maximum XOR of Two Numbers in an Array 
Medium 

423 
Reconstruct Original Digits from English 
Medium 

424 
Longest Repeating Character Replacement 
Medium 

426 
Convert Binary Search Tree to Sorted Doubly Linked List 
Medium 
Linked List 
Divide an Conquer 
Tree

427 
Construct Quad Tree 
Medium 

428 
Serialize and Deserialize Nary Tree 
Hard 
Tree

429 
Nary Tree Level Order Traversal 
Medium 
Tree

Breadthfirst Search

430 
Flatten a Multilevel Doubly Linked List 
Medium 

431 
Encode Nary Tree to Binary Tree 
Hard 
Tree

432 
All O`one Data Structure 
Hard 

433 
Minimum Genetic Mutation 
Medium 

434 
Number of Segments in a String 
Easy 

435 
Nonoverlapping Intervals 
Medium 

436 
Find Right Interval 
Medium 

437 
Path Sum III 
Medium 
Tree

438 
Find All Anagrams in a String 
Medium 

440 
Kth Smallest in Lexicographical Order 
Hard 

441 
Arranging Coins 
Easy 

442 
Find All Duplicates in an Array 
Medium 

443 
String Compression 
Medium 

444 
Sequence Reconstruction 
Medium 

445 
Add Two Numbers II 
Medium 

446 
Arithmetic Slices II  Subsequence 
Hard 

447 
Number of Boomerangs 
Medium 

448 
Find All Numbers Disappeared in an Array 
Easy 

449 
Serialize and Deserialize BST 
Medium 
Tree

450 
Delete Node in a BST 
Medium 
Tree

451 
Sort Characters By Frequency 
Medium 

452 
Minimum Number of Arrows to Burst Balloons 
Medium 

453 
Minimum Moves to Equal Array Elements 
Easy 

454 
4Sum II 
Medium 

455 
Assign Cookies 
Easy 

456 
132 Pattern 
Medium 

457 
Circular Array Loop 
Medium 

458 
Poor Pigs 
Hard 

459 
Repeated Substring Pattern 
Easy 

460 
LFU Cache 
Hard 

461 
Hamming Distance 
Easy 

462 
Minimum Moves to Equal Array Elements II 
Medium 

463 
Island Perimeter 
Easy 

464 
Can I Win 
Medium 

466 
Count The Repetitions 
Hard 

467 
Unique Substrings in Wraparound String 
Medium 

468 
Validate IP Address 
Medium 

470 
Implement Rand10() Using Rand7() 
Medium 

472 
Concatenated Words 
Hard 

473 
Matchsticks to Square 
Medium 

474 
Ones and Zeroes 
Medium 

475 
Heaters 
Medium 

476 
Number Complement 
Easy 

477 
Total Hamming Distance 
Medium 

478 
Generate Random Point in a Circle 
Medium 

479 
Largest Palindrome Product 
Hard 

480 
Sliding Window Median 
Hard 

481 
Magical String 
Medium 

482 
License Key Formatting 
Easy 

483 
Smallest Good Base 
Hard 

485 
Max Consecutive Ones 
Easy 

486 
Predict the Winner 
Medium 

488 
Zuma Game 
Hard 

491 
Increasing Subsequences 
Medium 

492 
Construct the Rectangle 
Easy 

493 
Reverse Pairs 
Hard 

494 
Target Sum 
Medium 

495 
Teemo Attacking 
Medium 

496 
Next Greater Element I 
Easy 

497 
Random Point in Nonoverlapping Rectangles 
Medium 

498 
Diagonal Traverse 
Medium 

500 
Keyboard Row 
Easy 
