Syncing Up

go/hexadecimal/hexadecimal.go

@@ -2,8 +2,6 @@ package hexadecimal
 
 import (
 	"errors"
-	"fmt"
-	"math/big"
 	"strings"
 )
 
@@ -14,43 +12,42 @@ func ParseHex(in string) (int64, error) {
 func HandleErrors(in []string) []string {
 	var ret []string
 	for i := range in {
+		errStr := "none"
 		_, err := convertNumStringBase(in[i], 16)
-		ret = append(ret, err.Error())
+		if err != nil {
+			errStr = err.Error()
+		}
+		ret = append(ret, errStr)
 	}
 	return ret
 }
 
 // convertNumStringBase takes a numeric string and the base of that string
 // and returns an int64 of the decimal representation
-func convertNumStringBase(in string, oldBase int64) (int64, error) {
+func convertNumStringBase(in string, base int64) (int64, error) {
 	if in == "" {
 		return 0, errors.New("syntax")
 	}
 	in = strings.ToLower(in)
-	base := big.NewInt(oldBase)
-	var sum big.Int
+	var a, n int64
 	for i := range in {
-		var x *big.Int
-		if in[i] >= '0' && in[i] <= '9' {
-			x = big.NewInt(int64(in[i] - '0'))
-		} else if in[i] >= 'a' && in[i] <= 'z' {
-			x = big.NewInt(int64(in[i]-'a') + 10)
-		}
-		fmt.Println("Comparing Converted Value ", x, "<", oldBase)
-		if x.Int64() > oldBase {
+		n *= base
+		switch {
+		case in[i] >= '0' && in[i] <= '9':
+			a = int64(in[i] - '0')
+		case in[i] >= 'a' && in[i] <= 'f':
+			a = int64(in[i]-'a') + 10
+		default:
 			return 0, errors.New("syntax")
 		}
+		if a > base {
+			return 0, errors.New("syntax")
+		}
+		n += a
 
-		pow := big.NewInt(int64(len(in) - i - 1))
-
-		var n big.Int
-		n.Exp(base, pow, nil)
-		n.Mul(x, &n)
-
-		sum.Add(&sum, &n)
-		if sum.Int64() < 0 {
-			return 0, errors.New("Integer Overflow")
+		if n < 0 {
+			return 0, errors.New("range")
 		}
 	}
-	return sum.Int64(), nil
+	return n, nil
 }