Merge pull request #2 from kevinwin/ch1

code for chapter 1 in javascript

01_introduction_to_algorithms/javascript/01_binary_search.js

@@ -0,0 +1,26 @@
+'use strict';
+
+function binary_search(list, item) {
+  let low = 0;
+  let high = list.length - 1;
+  
+  while (low <= high) {
+    let mid = Math.floor((low + high) / 2);
+    let guess = 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