From 48a1e121a369934d8803ee733ab20b5bb36cfaf0 Mon Sep 17 00:00:00 2001
From: DimVlas <DimVlasFd@gmail.com>
Date: Sat, 13 Apr 2024 11:38:55 +0300
Subject: [PATCH] =?UTF-8?q?hw02=20=D0=BE=D1=81=D0=BD=D0=BE=D0=B2=D0=BD?=
 =?UTF-8?q?=D0=BE=D0=B5=20=D0=B7=D0=B0=D0=B4=D0=B0=D0=BD=D0=B8=D0=B5?=
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---
 hw02_unpack_string/unpack.go      | 64 +++++++++++++++++++++++++++++--
 hw02_unpack_string/unpack_test.go | 25 +++++++++++-
 2 files changed, 84 insertions(+), 5 deletions(-)

diff --git a/hw02_unpack_string/unpack.go b/hw02_unpack_string/unpack.go
index 41f003d..f5746c1 100644
--- a/hw02_unpack_string/unpack.go
+++ b/hw02_unpack_string/unpack.go
@@ -2,11 +2,67 @@ package hw02unpackstring
 
 import (
 	"errors"
+	"fmt"
+	"slices"
+	"strconv"
+	"strings"
 )
 
-var ErrInvalidString = errors.New("invalid string")
+var (
+	ErrInvalidString = errors.New("invalid string")
 
-func Unpack(_ string) (string, error) {
-	// Place your code here.
-	return "", nil
+	nums = []rune{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'}
+
+	numZero = '0'
+)
+
+// True - если руна является цифрой.
+func IsDigit(r rune) bool {
+	return slices.Contains(nums, r)
+}
+
+func Unpack(text string) (string, error) {
+	if text == "" { // с пустой строкой ничего не делаем
+		return "", nil
+	}
+
+	runes := []rune(text)
+
+	if IsDigit(runes[0]) { // если первая руна цифра
+		return "", ErrInvalidString
+	}
+
+	var res strings.Builder
+
+	lenRunes := len(runes)
+	for i := 0; i < lenRunes; i++ {
+		if IsDigit(runes[i]) {
+			return "", ErrInvalidString
+		}
+
+		if i == lenRunes-1 { // это последний символ
+			res.WriteRune(runes[i])
+			break
+		}
+		if !IsDigit(runes[i+1]) { // следующий символ не цифра
+			res.WriteRune(runes[i])
+			continue
+		}
+		if IsDigit(runes[i+1]) { // следующий символ цифра
+			if runes[i+1] == numZero { // следующий символ '0'
+				i++
+				continue
+			}
+			n, err := strconv.Atoi(string(runes[i+1]))
+			if err != nil {
+				return "", fmt.Errorf("error converting rune '%q' to number: %w", runes[i+1], err)
+			}
+
+			res.WriteString(strings.Repeat(string(runes[i]), n))
+			i++
+			continue
+		}
+	}
+
+	return res.String(), nil
 }
diff --git a/hw02_unpack_string/unpack_test.go b/hw02_unpack_string/unpack_test.go
index 9799e18..73dfe8c 100644
--- a/hw02_unpack_string/unpack_test.go
+++ b/hw02_unpack_string/unpack_test.go
@@ -13,6 +13,9 @@ func TestUnpack(t *testing.T) {
 		expected string
 	}{
 		{input: "a4bc2d5e", expected: "aaaabccddddde"},
+		{input: "a4bc2d5e3", expected: "aaaabccdddddeee"},
+		{input: "a4bc2d5e0", expected: "aaaabccddddd"},
+		{input: "a+3b", expected: "a+++b"},
 		{input: "abccd", expected: "abccd"},
 		{input: "", expected: ""},
 		{input: "aaa0b", expected: "aab"},
@@ -34,7 +37,7 @@ func TestUnpack(t *testing.T) {
 }
 
 func TestUnpackInvalidString(t *testing.T) {
-	invalidStrings := []string{"3abc", "45", "aaa10b"}
+	invalidStrings := []string{"3abc", "45", "aaa10b", "aaa+b10"}
 	for _, tc := range invalidStrings {
 		tc := tc
 		t.Run(tc, func(t *testing.T) {
@@ -43,3 +46,23 @@ func TestUnpackInvalidString(t *testing.T) {
 		})
 	}
 }
+
+func TestIsDigit(t *testing.T) {
+	tests := []struct {
+		input    rune
+		expected bool
+	}{
+		{input: 'a', expected: false},
+		{input: '5', expected: true},
+		{input: '!', expected: false},
+		{input: '\n', expected: false},
+	}
+
+	for _, tc := range tests {
+		tc := tc
+		t.Run(string(tc.input), func(t *testing.T) {
+			result := IsDigit(tc.input)
+			require.Equal(t, tc.expected, result)
+		})
+	}
+}