Create count-binary-substrings.cpp

Author: kamyu104

C++/count-binary-substrings.cpp

@@ -0,0 +1,19 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    int countBinarySubstrings(string s) {
+        auto result = 0, prev = 0, curr = 1;
+        for (int i = 1; i < s.length(); ++i) {
+            if (s[i - 1] != s[i]) {
+                result += min(prev, curr);
+                prev = curr, curr = 1;
+            } else {
+                ++curr;
+            }
+        }
+        result += min(prev, curr);
+        return result;
+    }
+};