907

class Solution:
    def sumSubarrayMins(self, arr: List[int]) -> int:
        n = len(arr)
        next_lte = [n - i for i in range(n)]
        prev_lt = [i + 1 for i in range(n)]
        st_inc = []

        for i, num in enumerate(arr):
            while st_inc and num < arr[st_inc[-1]]:
                x = st_inc.pop()
                next_lte[x] = i - x
            if st_inc:
                prev_lt[i] = i - st_inc[-1]
            st_inc.append(i)

        res = 0

        for i in range(len(arr)):
            res += next_lte[i] * prev_lt[i] * arr[i]

        return res % (10**9 + 7)