From b867cd616a49f2c80b5558df3193c00d0f4fd8d8 Mon Sep 17 00:00:00 2001
From: Dan Buch <daniel.buch@gmail.com>
Date: Sun, 18 Nov 2012 20:19:47 -0500
Subject: [PATCH] Adding implementation of binary search rank

---
 .../src/meatballhat.com/algs4/binarysearch.go | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 algs4/src/meatballhat.com/algs4/binarysearch.go

diff --git a/algs4/src/meatballhat.com/algs4/binarysearch.go b/algs4/src/meatballhat.com/algs4/binarysearch.go
new file mode 100644
index 0000000..7d51f0f
--- /dev/null
+++ b/algs4/src/meatballhat.com/algs4/binarysearch.go
@@ -0,0 +1,21 @@
+package algs4
+
+func BinarySearchRank(key int, a []int) int {
+    lo := 0
+    hi := len(a) - 1
+
+    var mid int
+
+    for lo <= hi {
+        mid = lo + (hi - lo) / 2
+        if key < a[mid] {
+            hi = mid - 1
+        } else if key > a[mid] {
+            lo = mid + 1
+        } else {
+            return mid
+        }
+    }
+
+    return -1
+}