Create 1513. Number of Substrings With Only 1s (#934)

Author: Chayandas07

1513. Number of Substrings With Only 1s

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+class Solution {
+public:
+    static const int M = 1000000007;
+
+    int numSub(string s) {
+        long long ans = 0;
+        long long count1 = 0;
+
+        for (char ch : s) {
+            if (ch == '1') {
+                count1++;
+                ans = (ans + count1) % M;
+            } else {
+                count1 = 0;
+            }
+        }
+
+        return (int)ans;
+    }
+};