0040-combination-sum-ii.rb

def combination_sum2(candidates, target)
    @candidates = candidates
    @candidates.sort!
    @result = []

    def backtrack (cur,pos,target)
        @result.append(cur.dup()) if target == 0
        return if target <=0

        prev = -1

        (pos..@candidates.length-1).each do |i|
            next if @candidates[i] == prev

            cur.append(@candidates[i])

            backtrack(cur,i+1,target-@candidates[i])

            cur.pop()

            prev = @candidates[i]

        end

    end
    backtrack([],0,target)

    return @result

    
end