217. contains duplicate https://leetcode.com/problems/contains-duplicate/description/

• task description

242. Valid anagram https://leetcode.com/problems/valid-anagram/description/

• task description

1. Two sum https://leetcode.com/problems/two-sum/ #hashing #iterate

• task description

49. Group anagrams https://leetcode.com/problems/group-anagrams/ #hashing

• task description

36. Valid sudoku https://leetcode.com/problems/valid-sudoku/description/ #hashing

• task description

238. Product of array except self https://leetcode.com/problems/product-of-array-except-self/description/ #prefixes-postfixes