Filling in example binary search thing with real implementation

algs4/src/meatballhat.com/algs4-binarysearch/main.go

@@ -11,18 +11,38 @@ import (
 	"meatballhat.com/algs4"
 )
 
-func main() {
-	whiteList, err := algs4.ReadInts(bufio.NewReader(os.Stdin))
-	sort.Ints(whiteList)
+const USAGE string = `Usage: algs4-binarysearch <whitelist-file>
 
+You must also provide input on stdin.`
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Println(USAGE)
+		os.Exit(2)
+	}
+
+	whiteListFile, err := os.Open(string(os.Args[1]))
+	if err != nil {
+		fmt.Println("Failed to open whitelist file:", err)
+	}
+
+	whiteList, err := algs4.ReadInts(bufio.NewReader(whiteListFile))
 	if err != nil {
 		fmt.Println("UGH: ", err)
 		os.Exit(1)
 	}
 
-	fmt.Println("Sorted whitelist:")
+	sort.Ints(whiteList)
 
-	for i := range whiteList {
-		fmt.Println(i)
+	inputs, err := algs4.ReadInts(bufio.NewReader(os.Stdin))
+	if err != nil {
+		fmt.Println("Failed to read inputs:", err)
+		os.Exit(1)
+	}
+
+	for _, key := range inputs {
+		if algs4.BinarySearchRank(key, whiteList) == -1 {
+			fmt.Println(key)
+		}
 	}
 }