class NumArray

=begin
    :type nums: Integer[]
=end
    def initialize(nums)
        @dp = [nums[0]]
        (1...nums.size).each do |i|
            @dp[i] = @dp[i-1] + nums[i]
        end
    end


=begin
    :type i: Integer
    :type j: Integer
    :rtype: Integer
=end
    def sum_range(i, j)
        return @dp[j] if i == 0
        @dp[j] - @dp[i-1]
    end


end