Commit cf3c698

@@ -0,0 +1,25 @@
+require "spec_helper"
+
+def binary_search(items, target)
+  lo = 1
+  hi = items.size
+  while lo <= hi
+    mid = lo + (hi-lo)/2
+    if items[mid] == target
+      return items[mid]
+    elsif items[mid] < target
+      lo = mid + 1
+    else
+      hi = mid - 1
+    end
+  end
+  nil
+end
+
+describe "binary search" do
+  it "should find the number" do
+    items = [0, 5, 13, 19, 22, 41, 55, 68, 72, 81, 98]
+    result = binary_search(items, 55)
+    result.should == 55
+  end
+end