My solutions for leetcode problems

I've started solving some leetcode problems with a goal to improve in Prolog and Haskell. Unfortunately leetcode doesn't support neither of these languages and probably will never support Prolog, so I can't check whether my solution would be accepted.

Easy

#	Name	File

Medium

#	Name	File
15	3Sum	n_sum.pl
16	3Sum Closest	n_sum.pl
17	Letter Combinations of a Phone Number	letter_combinations.pl
18	4Sum	n_sum.pl
22	Generate Parentheses	generate_parentheses.hs
39	Combination Sum	combination_sum_i_ii.pl
40	Combination Sum II	combination_sum_i_ii.pl
47	Permutations II	permutations_ii.hs
48	Rotate Image	rotate_image.hs
49	Group Anagrams	group_anagrams.pl
55	Jump Game	jump_game_i_ii.hs
71	Simplify Path	unix_path_simplifier.hs
78	Subsets	subsets_i_ii.pl
90	Subsets II	subsets_i_ii.pl
93	Restore IP Addresses	restore_ip_addresses.pl
95	Unique Binary Search Trees II	unique_bsts_i_ii.pl
96	Unique Binary Search Trees	unique_bsts_i_ii.pl
98	Validate Binary Search Tree	validate_bst.pl
179	Largest Number	largest_number.hs
187	Repeated DNA Sequences	repeated_dna_seq.hs
670	Maximum Swap	maximum_swap.hs
921	Minimum Add to Make Parentheses Valid	parentheses_valid_changes_count.hs

Hard

#	Name	File
4	Median of Two Sorted Arrays	median_of_two_sorted_arrays.hs
32	Longest Valid Parentheses	longest_valid_parentheses.hs
45	Jump Game II	jump_game_i_ii.hs
87	Scramble String	scramble_string.hs