> map ... two arrays If we're allowed to use more memory than a simple stack, this is my favorite super-cheaty solution. It abuses ruby's builtin string manipu

> map ... two arrays If we're allowed to use more memory than a simple stack, this is my favorite super-cheaty solution. It abuses ruby's builtin string manipulation to recursively delete inner matched pairs (all that is really needed is a "slide remaining string left 2 chars" function). Since this only needs to match two-char long inner pairs, it trivially extends to multiple matched bracket types. BRACKET_RE = /\(\)/ #BRACKET_RE = /\(\)|\[\]|\{\}/ def balanced?(str) case str when '' then return true when BRACKET_RE then balanced? str.split(BRACKET_RE).join('') else return false end end