Sum of Subarray Minimum

Given an array of integers arr, find the sum of min(b), where b ranges over every (contiguous) subarray of arr. Since the answer may be large, return the answer modulo (10^9 + 7).

Example Inputs & Outputs

// Example 1:
Input: arr = [11, 81, 94, 43, 3]
Output: 444

// Example 2:
Input: arr = [2,2,2]
Output: 12

Constraints

• 1 <= arr.length <= 3 * 10^4
• 1 <= arr[i] <= 3 * 10^4

Edge Cases

• The array contains positive integers only.
• The result must be computed modulo (10^9 + 7).
• Single element array should return the element itself.
• Arrays with identical elements or repeating patterns may require careful handling to avoid overflow.