Practice Hub
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Reverse String
easyWrite a function that reverses a string. The input string is given as an array of characters `s`.
string two-pointers
Two Sum
easyGiven an array of integers `nums` and an integer `target`, return indices of the two numbers such that they add up to `target`.
array hash-table
Valid Parentheses
easyGiven a string `s` containing just the characters `'('`, `')'`, `'{'`, `'}'`, `'['` and `']'`, determine if the input string is valid.
string stack