# Status Problem video Level Completes Likes 438 Check if interval is covered in given coordinates Medium % 0 437 Lexicographically previous permutation With One swap Medium % 1 436 Find all unique combinations of exact K numbers (from 1 to 9 ) with sum to N Medium % 0 431 Check the completeness of given binary tree | Set 1 - Using Node Count Medium % 0 428 Collatz Conjecture - Maximum Steps takes to transform (1, N) to 1. Medium % 0 427 Number of Islands using BFS Medium % 0 426 Check if Graph is Bipartite - Adjacency List using Depth-First Search(DFS) Hard % 0 425 Check if the given binary tree is Full or not Beginner % 1 422 Print Stack in reverse order Beginner % 0 421 Sort a given stack - Using Recursion Hard % 1 420 Number's Complement - 2 Approaches Medium % 1 419 Print all subsets of an array with a sum equal to zero Medium % 0 417 Maximum number edges to make Acyclic Undirected/Directed Graph Beginner % 0 416 Evaluation of Prefix Expressions (Polish Notation) | Set 2 Medium % 0 413 ZigZag OR Diagonal traversal in 2d array/Matrix using queue Medium % 0 410 Evaluation of Prefix Expressions (Polish Notation) | Set 1 Medium % 0 409 Minimum Boats Required to rescue people Medium % 0 408 Number of Islands Medium % 1 407 Integer Replacement Problem Medium % 0 406 Evaluation of Postfix Expressions (Polish Postfix notation) | Set 2 Medium % 0 Check if interval is covered in given coordinates Lexicographically previous permutation With One swap Find all unique combinations of exact K numbers (from 1 to 9 ) with sum to N Check the completeness of given binary tree | Set 1 - Using Node Count Collatz Conjecture - Maximum Steps takes to transform (1, N) to 1. Number of Islands using BFS Check if Graph is Bipartite - Adjacency List using Depth-First Search(DFS) Check if the given binary tree is Full or not Print Stack in reverse order Sort a given stack - Using Recursion Number's Complement - 2 Approaches Print all subsets of an array with a sum equal to zero Maximum number edges to make Acyclic Undirected/Directed Graph Evaluation of Prefix Expressions (Polish Notation) | Set 2 ZigZag OR Diagonal traversal in 2d array/Matrix using queue Evaluation of Prefix Expressions (Polish Notation) | Set 1 Minimum Boats Required to rescue people Number of Islands Integer Replacement Problem Evaluation of Postfix Expressions (Polish Postfix notation) | Set 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15