Merge pull request #2326 from FarmerChillax/master

Update 0242.有效的字母异位词，添加第二种Go解法

problems/0242.有效的字母异位词.md

@@ -181,6 +181,31 @@ func isAnagram(s string, t string) bool {
 }
 ```
 
+Go 写法二(只对字符串遍历一次)
+```go
+func isAnagram(s string, t string) bool {
+	if len(s) != len(t) {
+		return false
+	}
+	records := [26]int{}
+	for index := 0; index < len(s); index++ {
+		if s[index] == t[index] {
+			continue
+		}
+		sCharIndex := s[index] - 'a'
+		records[sCharIndex]++
+		tCharIndex := t[index] - 'a'
+		records[tCharIndex]--
+	}
+	for _, record := range records {
+		if record != 0 {
+			return false
+		}
+	}
+	return true
+}
+```
+
 ### JavaScript:
 
 ```js