1using System;
2using System.Collections.Generic;
3
4public class Solution {
5    public int SumSubarrayMins(int[] arr) {
6        const int MOD = (int)1e9 + 7;
7        int n = arr.Length;
8        Stack<int> stack = new Stack<int>();
9        long sum = 0;
10
11        for (int i = 0; i <= n; i++) {
12            while (stack.Count > 0 && (i == n || arr[stack.Peek()] >= arr[i])) {
13                int index = stack.Pop();
14                int curValue = arr[index];
15                int left = stack.Count == 0 ? index + 1 : index - stack.Peek();
16                int right = i - index;
17                sum = (sum + (long)curValue * left * right) % MOD;
18            }
19            stack.Push(i);
20        }
21
22        return (int)sum;
23    }
24}

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