add code for chapters 1 and 2 in ts (#102)

01_introduction_to_algorithms/ts/01_binary_search.ts

@@ -0,0 +1,24 @@
+function binary_search<T>(list: T[], item: T): number | null {
+  let low: number = 0;
+  let high: number = list.length - 1;
+
+  while (low <= high) {
+    let mid: number = Math.floor((low + high) / 2);
+    let guess: T = list[mid];
+    if (guess === item) {
+      return mid;
+    }
+    if (guess > item) {
+      high = mid - 1;
+    } else {
+      low = mid + 1;
+    }
+  }
+
+  return null;
+}
+
+const my_list = [1, 3, 5, 7, 9];
+
+console.log(binary_search(my_list, 3)); // 1
+console.log(binary_search(my_list, -1)); // null