add gcd command

cmd/gcd.go

@@ -0,0 +1,66 @@
+/*
+Copyright © 2025 filifa
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+package cmd
+
+import (
+	"fmt"
+	"log"
+	"math/big"
+
+	"github.com/spf13/cobra"
+)
+
+func gcd(cmd *cobra.Command, args []string) {
+	var x big.Int
+	var y big.Int
+	var z big.Int
+	var w big.Int
+
+	for _, s := range args {
+		_, ok := w.SetString(s, 10)
+		if !ok {
+			log.Fatal("invalid input " + s)
+		}
+
+		z.GCD(&x, &y, &z, &w)
+	}
+
+	fmt.Println(&z)
+}
+
+// gcdCmd represents the gcd command
+var gcdCmd = &cobra.Command{
+	Use:   "gcd",
+	Short: "Compute the greatest common denominator of a set of numbers",
+	Long:  `Compute the greatest common denominator of a set of numbers.`,
+	Args:  cobra.MinimumNArgs(2),
+	Run:   gcd,
+}
+
+func init() {
+	rootCmd.AddCommand(gcdCmd)
+
+	// Here you will define your flags and configuration settings.
+
+	// Cobra supports Persistent Flags which will work for this command
+	// and all subcommands, e.g.:
+	// gcdCmd.PersistentFlags().String("foo", "", "A help for foo")
+
+	// Cobra supports local flags which will only run when this command
+	// is called directly, e.g.:
+	// gcdCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
+}