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huffman_decoding.go
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/
huffman_decoding.go
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package main
import (
"bufio"
"fmt"
"os"
"strings"
)
type HuffmanNode struct {
value rune
left *HuffmanNode
right *HuffmanNode
}
func buildTree(codes map[rune]string) *HuffmanNode {
root := &HuffmanNode{}
var current *HuffmanNode
for ch := range codes {
current = root
for _, code := range codes[ch] {
if code == '0' {
if current.left == nil {
current.left = &HuffmanNode{}
}
current = current.left
} else {
if current.right == nil {
current.right = &HuffmanNode{}
}
current = current.right
}
}
current.value = ch
}
return root
}
func huffmanDecode(codes map[rune]string, encoded string) string {
root := buildTree(codes)
var result strings.Builder
result.Grow(64)
current := root
for _, code := range encoded {
if code == '0' {
current = current.left
} else {
current = current.right
}
if current.value != 0 {
result.WriteRune(current.value)
current = root
}
}
return result.String()
}
func main() {
stdin, err := os.Open(os.Getenv("INPUT_PATH"))
if err != nil {
stdin = os.Stdin
}
defer stdin.Close()
stdout, err := os.Create(os.Getenv("OUTPUT_PATH"))
if err != nil {
stdout = os.Stdout
}
defer stdout.Close()
reader := bufio.NewReaderSize(stdin, 1024*1024)
writer := bufio.NewWriterSize(stdout, 1024*1024)
var k, l int
_, err = fmt.Fscanln(reader, &k, &l)
checkError(err)
codes := make(map[rune]string)
var letter rune
var code string
for ; k > 0; k-- {
_, err = fmt.Fscanf(reader, "%c: %s\n", &letter, &code)
checkError(err)
codes[letter] = code
}
var encoded string
_, err = fmt.Fscan(reader, &encoded)
checkError(err)
str := huffmanDecode(codes, encoded)
fmt.Fprint(writer, str)
writer.Flush()
}
func checkError(err error) {
if err != nil {
panic(err)
}
}