Compression

Author: plutov

.github/workflows/lint-test.yaml

@@ -0,0 +1,40 @@
+name: Lint and Test
+
+on: push
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.21.x"
+      - name: Install dependencies
+        run: go get .
+      - name: Install linters
+        run: |
+          go install honnef.co/go/tools/cmd/staticcheck@latest
+          go install mvdan.cc/unparam@latest
+      - name: go vet
+        run: go vet ${{ inputs.path }}
+      - name: staticcheck
+        run: staticcheck ${{ inputs.path }}
+      - name: unparam
+        run: unparam ${{ inputs.path }}
+
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.21.x"
+      - name: Install dependencies
+        run: go get .
+      - name: Run Tests
+        run: go test -v ./...

README.md

@@ -34,6 +34,7 @@
  - [x] ([@shogg](https://github.com/shogg)) [brokennode](https://github.com/plutov/practice-go/tree/master/brokennode)
  - [x] ([@shogg](https://github.com/shogg)) [nasacollage](https://github.com/plutov/practice-go/tree/master/nasacollage)
 - [x] ([@shogg](https://github.com/shogg)) [node_degree](https://github.com/plutov/practice-go/tree/master/node_degree)
+- [ ] [compression](https://github.com/plutov/practice-go/tree/master/compression)
 
 ### Run tests with benchmarks
 

anagram/anagram.go

@@ -14,7 +14,7 @@ func (r MyRune) Less(i, j int) bool { return r[i] < r[j] }
 
 func Normalize(s string) string {
 	var r MyRune
-	for _, b := range []rune(s) {
+	for _, b := range s {
 		b = unicode.ToLower(b)
 		if b >= 'a' && b <= 'z' {
 			r = append(r, b)
@@ -32,7 +32,7 @@ func FindAnagrams(dictionary []string, word string) (result []string) {
 	var res []string
 	for _, s := range dictionary {
 		n2 := Normalize(s)
-		if n == n2 && strings.ToLower(s) != strings.ToLower(word) {
+		if n == n2 && !strings.EqualFold(s, word) {
 			res = append(res, s)
 		}
 	}

anagram/anagram_test.go

@@ -2,7 +2,7 @@ package anagram
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strings"
 	"testing"
 )
@@ -25,7 +25,7 @@ var tests = []struct {
 }
 
 func init() {
-	content, err := ioutil.ReadFile("dictionary.txt")
+	content, err := os.ReadFile("dictionary.txt")
 	if err != nil {
 		panic(err)
 	}

chess/chess.go

@@ -11,10 +11,10 @@ func CanKnightAttack(white, black string) (bool, error) {
 
 	// Check if pieces are on board
 	if white[0]-'a' > 7 || white[1]-'1' > 7 {
-		return false, errors.New("Invalid white position")
+		return false, errors.New("invalid white position")
 	}
 	if black[0]-'a' > 7 || black[1]-'1' > 7 {
-		return false, errors.New("Invalid black position")
+		return false, errors.New("invalid black position")
 	}
 
 	// Calculate distance between knights in each axis
@@ -25,7 +25,7 @@ func CanKnightAttack(white, black string) (bool, error) {
 	if (d0 == 1 && d1 == 2) || (d0 == 2 && d1 == 1) {
 		return true, nil
 	} else if d0 == 0 && d1 == 0 {
-		return false, errors.New("You can't stack 'em you silly.")
+		return false, errors.New("you cannot stack them you silly")
 	}
 	return false, nil
 }

compression/README.md

@@ -0,0 +1,20 @@
+### Build a compression
+
+This challenge focuses on creating a simple lossless compression tool from scratch. You'll need to implement an algorithm to achieve compression without relying on external libraries, you can use a known algorithm though (for example Huffman). The goal is to balance compression ratio (how much smaller the compressed file is compared to the original) and compression/decompression speed.
+
+This challenge will help you understand the concepts of data compression, explore different algorithms, and practice efficient data structure design. You'll also gain experience in balancing performance and resource usage.
+
+### Sample data set
+
+This challenge includes a sample `dataset.txt` (3.2MB) file which will be used in benchmarking.
+
+### Functions
+
+- `Encode(s string) string`
+- `Decode(s string) string`
+
+### Run tests with benchmarks
+
+```
+go test -bench .
+```

compression/compression.go

@@ -0,0 +1,9 @@
+package compression
+
+func Encode(s string) string {
+	return s
+}
+
+func Decode(s string) string {
+	return s
+}

compression/compression_test.go

@@ -0,0 +1,39 @@
+package compression
+
+import (
+	"fmt"
+	"os"
+	"testing"
+)
+
+var (
+	originalContent string
+	originalLength  int64
+)
+
+func init() {
+	code, _ := os.ReadFile("dataset.txt")
+	originalContent = string(code)
+
+	originalLength = int64(len(originalContent))
+}
+
+func TestEncodeDecode(t *testing.T) {
+	encoded := Encode(originalContent)
+	decoded := Decode(encoded)
+
+	if originalContent != decoded {
+		t.Errorf("Decode(Encode(originalContent)) = %s, want %s", decoded, originalContent)
+	}
+
+	// print compression ratio
+	encodedLength := int64(len(encoded))
+	fmt.Printf("\nOriginal length: %d, Encoded length: %d, Compression ratio: %.2f\n\n", originalLength, encodedLength, float64(encodedLength)/float64(originalLength))
+}
+
+func BenchmarkEncodeDecode(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		encoded := Encode(originalContent)
+		Decode(encoded)
+	}
+}