refactor: reduce a cognitive complexity (#18)

.codeclimate.yml

@@ -0,0 +1,24 @@
+---
+engines:
+  golint:
+    enabled: true
+    checks:
+      GoLint/Naming/MixedCaps:
+        enabled: true
+  govet:
+    enabled: true
+  gofmt:
+    enabled: true
+  fixme:
+    enabled: true
+  markdownlint:
+    enabled: true
+  shellcheck:
+    enabled: true
+ratings:
+  paths:
+    - '**.go'
+exclude_paths:
+  - '**/*_test.go'
+  - '*_test.go'
+  - 'vendor/'

platform/HackerRank/The-HackerRank-Interview-Preparation-Kit/3-Sorting/4-Fraudulent-Activity-Notifications/activity_notifications.go

@@ -10,59 +10,70 @@ const maxExpenditure = 201
 
 func activityNotifications(expenditures []int, d int) int {
 	var notifications int
-	var i, j int
+	histogram := buildHistogram(expenditures[:d])
 
-	histogram := make([]int, maxExpenditure)
-	for i = 0; i < d; i++ { //nolint: intrange
-		histogram[expenditures[i]]++
+	for n, i := len(expenditures), d; i < n; i++ {
+		doubleMedian := calculateDoubleMedian(histogram, d)
+
+		if expenditures[i] >= doubleMedian {
+			notifications++
+		}
+
+		// Update histogram: slide window 1 index to right
+		updateHistogram(histogram, expenditures[i-d], expenditures[i])
 	}
 
-	for n := len(expenditures); i < n; i++ {
-		doubleMedian := 0
+	return notifications
+}
 
-		cursor := 0
-		left := -1
+func buildHistogram(expenditures []int) []int {
+	histogram := make([]int, maxExpenditure)
+	for _, exp := range expenditures {
+		histogram[exp]++
+	}
 
-		for j = range maxExpenditure {
-			cursor += histogram[j]
-			if d%2 == 1 { //nolint: nestif
-				// Odd -> Pick middle one for median
-				if cursor >= d/2+1 {
-					doubleMedian = 2 * j
+	return histogram
+}
 
-					break
-				}
-			} else {
-				// Even -> Pick average of two middle values for median
-				if cursor == d/2 {
-					left = j
-				}
+func calculateDoubleMedian(histogram []int, days int) int {
+	var doubleMedian int
 
-				if cursor > d/2 && left != -1 {
-					right := j
-					doubleMedian = left + right
+	cursor := 0
+	left := -1
 
-					break
-				}
+	for j := range maxExpenditure {
+		cursor += histogram[j]
 
-				if cursor > d/2 && left == -1 {
-					doubleMedian = 2 * j
+		if days%2 == 1 { //nolint: nestif
+			// Odd
+			if cursor >= days/2+1 {
+				doubleMedian = 2 * j
 
-					break
-				}
+				break
 			}
-		}
+		} else {
+			// Even
+			if cursor == days/2 {
+				left = j
+			}
+			if cursor > days/2 {
+				if left != -1 {
+					doubleMedian = left + j
+				} else {
+					doubleMedian = 2 * j
+				}
 
-		if expenditures[i] >= doubleMedian {
-			notifications++
+				break
+			}
 		}
-
-		// Update histogram: slide window 1 index to right
-		histogram[expenditures[i-d]]--
-		histogram[expenditures[i]]++
 	}
 
-	return notifications
+	return doubleMedian
+}
+
+func updateHistogram(histogram []int, outgoing, incoming int) {
+	histogram[outgoing]--
+	histogram[incoming]++
 }
 
 func main() {

platform/HackerRank/The-HackerRank-Interview-Preparation-Kit/4-Dictionaries-and-Hashmaps/4-Frequency-Queries/frequency_queries.go

@@ -12,6 +12,31 @@ const (
 	CheckCase
 )
 
+func insertValue(value int, number, frequency map[int]int) {
+	freq := number[value]
+	number[value]++
+	frequency[number[value]]++
+	if freq > 0 {
+		frequency[freq]--
+	}
+}
+
+func deleteValue(value int, number, frequency map[int]int) {
+	if freq, ok := number[value]; ok {
+		number[value]--
+		if number[value] == 0 {
+			delete(number, value)
+		} else {
+			frequency[number[value]]++
+		}
+
+		frequency[freq]--
+		if frequency[freq] == 0 {
+			delete(frequency, freq)
+		}
+	}
+}
+
 func frequencyQueries(queries [][]int) []int {
 	var result []int
 
@@ -21,26 +46,9 @@ func frequencyQueries(queries [][]int) []int {
 	for _, query := range queries {
 		switch action, value := query[0], query[1]; action {
 		case InsertCase:
-			freq := number[value]
-			number[value]++
-			frequency[number[value]]++
-			if freq > 0 {
-				frequency[freq]--
-			}
+			insertValue(value, number, frequency)
 		case DeleteCase:
-			if freq, ok := number[value]; ok {
-				number[value]--
-				if number[value] == 0 {
-					delete(number, value)
-				} else {
-					frequency[number[value]]++
-				}
-
-				frequency[freq]--
-				if frequency[freq] == 0 {
-					delete(frequency, freq)
-				}
-			}
+			deleteValue(value, number, frequency)
 		case CheckCase:
 			item := 0
 			if freq, ok := frequency[value]; ok && freq > 0 {