Create 907.py

Author: chandansgowda

501-1000/907.py

@@ -0,0 +1,12 @@
+class Solution:
+    def sumSubarrayMins(self, arr: List[int]) -> int:
+        ans = 0
+        stack = [] 
+        arr = [float('-inf')] + arr + [float('-inf')]
+        for i, n in enumerate(arr):
+            while stack and arr[stack[-1]] > n:
+                cur = stack.pop()
+                ans += arr[cur] * (i - cur) * (cur - stack[-1]) 
+            stack.append(i)
+        return ans % (10**9 + 7)
+