Create 907 Sum of Subarray Minimums.cpp

Author: Meghak1

907 Sum of Subarray Minimums.cpp

@@ -0,0 +1,20 @@
+class Solution {
+public:
+    int sumSubarrayMins(vector<int>& arr) {
+        int MOD=1000000007;
+        int n=arr.size();
+        long result=0;
+
+        vector<int> stack;
+        for (int i=0; i<=n; ++i) {
+           while (!stack.empty() && (i==n || arr[stack.back()]>arr[i])) {
+             int j=stack.back();
+             stack.pop_back();
+             int prev=stack.empty() ? -1:stack.back();
+             result=(result+(long long)arr[j] * (j-prev) * (i-j)) % MOD;
+            }
+         stack.push_back(i);
+      }
+     return result;
+    }
+};