Create binarysearch.lua

Author: sirwez

DataStructures/Trees/binarysearch.lua

@@ -0,0 +1,22 @@
+binarysearch = {}
+binarysearch.__index = binarysearch
+
+function binarysearch.indexOf(a, value, comparator)
+    local lo = 0
+    local hi = a:size() - 1
+    while lo <= hi do
+        local mid = lo + math.floor((hi - lo) / 2)
+        local cmp = comparator(value, a:get(mid))
+        if cmp < 0 then
+            hi = mid - 1
+        elseif cmp > 0 then
+            lo = mid + 1
+        else
+            return mid
+        end
+    end
+    return -1
+
+end
+
+return binarysearch