README.md

1508. Range Sum of Sorted Subarray Sums

Given the array nums consisting of n positive integers. You computed the sum of all non-empty continous subarrays from the array and then sort them in non-decreasing order, creating a new array of n * (n + 1) / 2 numbers.

Return the sum of the numbers from index left to index right (indexed from 1), inclusive, in the new array. Since the answer can be a huge number return it modulo 10^9 + 7.

Example 1:

Input: nums = [1,2,3,4], n = 4, left = 1, right = 5
Output: 13
Explanation: All subarray sums are 1, 3, 6, 10, 2, 5, 9, 3, 7, 4. After sorting them in non-decreasing order we have the new array [1, 2, 3, 3, 4, 5, 6, 7, 9, 10]. The sum of the numbers from index le = 1 to ri = 5 is 1 + 2 + 3 + 3 + 4 = 13.

Example 2:

Input: nums = [1,2,3,4], n = 4, left = 3, right = 4
Output: 6
Explanation: The given array is the same as example 1. We have the new array [1, 2, 3, 3, 4, 5, 6, 7, 9, 10]. The sum of the numbers from index le = 3 to ri = 4 is 3 + 3 = 6.

Example 3:

Input: nums = [1,2,3,4], n = 4, left = 1, right = 10
Output: 50

Constraints:

• 1 <= nums.length <= 10^3
• nums.length == n
• 1 <= nums[i] <= 100
• 1 <= left <= right <= n * (n + 1) / 2

Solutions (Ruby)

1. Solution

# @param {Integer[]} nums
# @param {Integer} n
# @param {Integer} left
# @param {Integer} right
# @return {Integer}
def range_sum(nums, _n, left, right)
  sums = []
  ret = 0

  (0...nums.size).each do |i|
    sum = 0
    (i...nums.size).each do |j|
      sum += nums[j]
      sums.push(sum)
    end
  end

  sums.sort!

  (left..right).each do |i|
    ret = (ret + sums[i - 1]) % 1_000_000_007
  end

  ret
end

Solutions (Rust)

1. Solution

impl Solution {
    pub fn range_sum(nums: Vec<i32>, n: i32, left: i32, right: i32) -> i32 {
        let mut sums = vec![];
        let mut ret = 0;

        for i in 0..nums.len() {
            let mut sum = 0;
            for j in i..nums.len() {
                sum += nums[j];
                sums.push(sum);
            }
        }

        sums.sort_unstable();

        for i in left..=right {
            ret = (ret + sums[i as usize - 1]) % 1_000_000_007;
        }

        ret
    }
}