"Substring With Concatenation of all words" hard task No 30 accepted solution

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
+}