From 93158bf5243f3aa8ef966148c1297fd443b7962a Mon Sep 17 00:00:00 2001
From: bavog81 <lera.bogdanova81@gmail.com>
Date: Wed, 3 Jul 2024 01:03:54 +0200
Subject: [PATCH] HW2 is completed

---
 hw02_unpack_string/unpack.go      | 43 ++++++++++++++++++++++++++++---
 hw02_unpack_string/unpack_test.go | 14 ++++++----
 2 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/hw02_unpack_string/unpack.go b/hw02_unpack_string/unpack.go
index 41f003d..6f4b90a 100644
--- a/hw02_unpack_string/unpack.go
+++ b/hw02_unpack_string/unpack.go
@@ -2,11 +2,48 @@ package hw02unpackstring
 
 import (
 	"errors"
+	"strconv"
+	"strings"
 )
 
 var ErrInvalidString = errors.New("invalid string")
 
-func Unpack(_ string) (string, error) {
-	// Place your code here.
-	return "", nil
+func Unpack(s string) (string, error) {
+	var result strings.Builder
+	k := false
+
+	for i, j := 0, 1; i < len(s); i, j = i+1, j+1 {
+		if !k {
+			_, error := strconv.Atoi(string(s[i]))
+			if error == nil {
+				return "", ErrInvalidString
+			}
+		}
+
+		b := string(s[i])
+
+		if b == "\\" && !k {
+			k = true
+			continue
+		}
+
+		if j < len(s) {
+			num, err := strconv.Atoi(string(s[j]))
+
+			if err == nil {
+				repstr := strings.Repeat(b, num)
+				result.WriteString(repstr)
+				i++
+				j++
+			} else {
+				result.WriteString(string(s[i]))
+			}
+		} else {
+			result.WriteString(string(s[i]))
+		}
+
+		k = false
+	}
+
+	return result.String(), nil
 }
diff --git a/hw02_unpack_string/unpack_test.go b/hw02_unpack_string/unpack_test.go
index 9799e18..c34e3b4 100644
--- a/hw02_unpack_string/unpack_test.go
+++ b/hw02_unpack_string/unpack_test.go
@@ -16,11 +16,15 @@ func TestUnpack(t *testing.T) {
 		{input: "abccd", expected: "abccd"},
 		{input: "", expected: ""},
 		{input: "aaa0b", expected: "aab"},
+		{input: "a0", expected: ""},
 		// uncomment if task with asterisk completed
-		// {input: `qwe\4\5`, expected: `qwe45`},
-		// {input: `qwe\45`, expected: `qwe44444`},
-		// {input: `qwe\\5`, expected: `qwe\\\\\`},
-		// {input: `qwe\\\3`, expected: `qwe\3`},
+		{input: `qwe\4\5`, expected: `qwe45`},
+		{input: `qwe\45`, expected: `qwe44444`},
+		{input: `qwe\\5`, expected: `qwe\\\\\`},
+		{input: `qwe\\\3`, expected: `qwe\3`},
+		{input: `a\00`, expected: `a`},
+		{input: `\0\\\`, expected: `0\`},
+		{input: `\0\\0`, expected: `0`},
 	}
 
 	for _, tc := range tests {
@@ -34,7 +38,7 @@ func TestUnpack(t *testing.T) {
 }
 
 func TestUnpackInvalidString(t *testing.T) {
-	invalidStrings := []string{"3abc", "45", "aaa10b"}
+	invalidStrings := []string{"3abc", "45", "aaa10b", "a0a0a01"}
 	for _, tc := range invalidStrings {
 		tc := tc
 		t.Run(tc, func(t *testing.T) {