From 9ebb71d76fdb70cd461120ed4ef9143a6427b3b1 Mon Sep 17 00:00:00 2001
From: Rostislav Kuratch <kr0st@bioreactor.me>
Date: Wed, 20 Apr 2022 16:42:03 +0300
Subject: [PATCH] "Substring With Concatenation of all words" hard task No 30
 accepted solution

---
 ...bstring-with-concatenation-of-all-words.go | 52 +++++++++++++++++++
 ...ng-with-concatenation-of-all-words_test.go | 33 ++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 30-substring-with-concatenation-of-all-words.go
 create mode 100644 30-substring-with-concatenation-of-all-words_test.go

diff --git a/30-substring-with-concatenation-of-all-words.go b/30-substring-with-concatenation-of-all-words.go
new file mode 100644
index 0000000..8feb983
--- /dev/null
+++ b/30-substring-with-concatenation-of-all-words.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+)
+
+func FindSubstring(s string, words []string) []int {
+
+	res := []int{}
+
+	numWords := len(words)
+	strLen := len(s)
+
+	if numWords == 0 || strLen == 0 {
+		return res
+	}
+
+	wordMapOriginal := map[string]int{}
+	for _, w := range words {
+		wordMapOriginal[w]++
+	}
+
+	jsonWordMapOriginal, _ := json.Marshal(wordMapOriginal)
+
+	wordSz := len(words[0])
+	wndSz := numWords * wordSz
+
+	for i := 0; i <= strLen-wndSz; i++ {
+		j := 0
+
+		wordMap := map[string]int{}
+
+		for j = i; j < i+wndSz; j += wordSz {
+			word := s[j : j+wordSz]
+			_, ok := wordMapOriginal[word]
+			if !ok {
+				break
+			} else {
+				wordMap[word]++
+			}
+		}
+		if j == i+wndSz {
+			jsonWordMap, _ := json.Marshal(wordMap)
+			if bytes.Compare(jsonWordMap, jsonWordMapOriginal) == 0 {
+				res = append(res, i)
+			}
+		}
+	}
+
+	return res
+}
diff --git a/30-substring-with-concatenation-of-all-words_test.go b/30-substring-with-concatenation-of-all-words_test.go
new file mode 100644
index 0000000..92b95ca
--- /dev/null
+++ b/30-substring-with-concatenation-of-all-words_test.go
@@ -0,0 +1,33 @@
+package main
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestFindSubstring128(t *testing.T) {
+	words := []string{"word", "good", "best", "good"}
+	expected := []int{8}
+	res := FindSubstring("wordgoodgoodgoodbestword", words)
+	assert.Equal(t, expected, res)
+}
+
+func TestFindSubstring0(t *testing.T) {
+	words := []string{"foo", "bar"}
+	expected := []int{0, 9}
+	res := FindSubstring("barfoothefoobarman", words)
+	assert.Equal(t, expected, res)
+}
+
+func TestFindSubstring1(t *testing.T) {
+	words := []string{"word", "good", "best", "word"}
+	expected := []int{}
+	res := FindSubstring("wordgoodgoodgoodbestword", words)
+	assert.Equal(t, expected, res)
+}
+func TestFindSubstring2(t *testing.T) {
+	words := []string{"bar", "foo", "the"}
+	expected := []int{6, 9, 12}
+	res := FindSubstring("barfoofoobarthefoobarman", words)
+	assert.Equal(t, expected, res)
+}