diff --git a/algorithm.ts b/algorithm.ts
new file mode 100644
index 0000000..9e89b8a
--- /dev/null
+++ b/algorithm.ts
@@ -0,0 +1,25 @@
+/**
+ * Performs a binary search within a specified range.
+ * @param begin The starting index of the search range.
+ * @param end The ending index of the search range.
+ * @param beforeHalf A list of predicates indicating conditions before the midpoint.
+ * @returns A tuple containing the indices representing the binary search state: [begin, half, end].
+ */
+export function binSearch(begin: number, end: number, beforeHalf: boolean[]): [number, number, number] {
+    const gHalf = () => { return Math.floor((end - begin) / 2) + begin; }
+
+    for (const pred of beforeHalf) {
+        const half = gHalf();
+        if (pred) {
+            // Happens before "half"
+            end = half;
+        } else {
+            begin = half;
+        }
+    }
+
+    const half = gHalf();
+    console.log(`Checking range: [${begin}, ${end}], ${end - begin} objects, mid ${half}`);
+
+    return [begin, half, end];
+}