diff --git a/interviews/think-cell/interview.cpp b/interviews/think-cell/interview.cpp
new file mode 100644
index 0000000..6f32611
--- /dev/null
+++ b/interviews/think-cell/interview.cpp
@@ -0,0 +1,47 @@
+
+//aschoedl@think-cell.com
+
+#include <iostream>
+#include <vector>
+
+template<typename T, typename IT>
+int binary_search(	IT ib, IT ie, const T& e )
+{
+	if ( ib == ie || e < *ib || *(ie-1) < e )
+		return -1;
+
+	auto base = ib;
+	auto im = (ib+(ie-ib)/2);
+	while ( ib != im )
+	{
+		if ( e < *im )
+			ie = im;
+		else
+			ib = im;
+		im = (ib+(ie-ib)/2);
+	}
+
+	return !(*ib < e) ? (ib - base) : -1;
+}
+
+void main ( void )
+{
+	std::vector<int> v = { 0,1,2,3,4,4,4,4,5,6,7,8,9,11};
+
+	for ( int i = 0; i < v.size(); i++ ) {
+		int j = binary_search( v.begin(), v.end(), v[i] );
+		std::cout << v[i] << "->" << j << std::endl;
+	}
+	std::cout << binary_search( v.begin(), v.end(), 10 ) << std::endl;
+	std::cout << binary_search( v.begin(), v.end(), 12 ) << std::endl;
+	std::cout << binary_search( v.begin(), v.end(), -4 ) << std::endl;
+
+	std::vector<int> v0;
+	std::cout << binary_search( v0.begin(), v0.end(), 10 ) << std::endl;
+
+	std::vector<int> v1 = { 1 };
+	std::cout << binary_search( v1.begin(), v1.end(), -10 ) << std::endl;
+	std::cout << binary_search( v1.begin(), v1.end(), 10 ) << std::endl;
+	std::cout << binary_search( v1.begin(), v1.end(), 1 ) << std::endl;
+}
+