From 6888f8fd5b7b38b68b76c42a4abbceb26901a07a Mon Sep 17 00:00:00 2001
From: edipretoro <edipretoro@gmail.com>
Date: Mon, 20 Jul 2026 07:03:18 +0200
Subject: [PATCH] Solving the challenge 0102

---
 0102/kv_entry.go | 49 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/0102/kv_entry.go b/0102/kv_entry.go
index bd356fd..a0d427f 100644
--- a/0102/kv_entry.go
+++ b/0102/kv_entry.go
@@ -1,6 +1,8 @@
 package db0102
 
 import (
+	"encoding/binary"
+	"errors"
 	"io"
 )
 
@@ -9,8 +11,51 @@ type Entry struct {
 	val []byte
 }
 
-func (ent *Entry) Encode() []byte
+func (ent *Entry) Encode() []byte {
+	data := make([]byte, 4+4+len(ent.key)+len(ent.val))
+	binary.LittleEndian.PutUint32(data[0:4], uint32(len(ent.key)))
+	binary.LittleEndian.PutUint32(data[4:8], uint32(len(ent.val)))
+	copy(data[8:], ent.key)
+	copy(data[8+len(ent.key):], ent.val)
+	return data
+}
 
-func (ent *Entry) Decode(r io.Reader) error
+func (ent *Entry) Decode(r io.Reader) error {
+	key_len := make([]byte, 4)
+	s, err := r.Read(key_len)
+	if err != nil {
+		return err
+	}
+	if s != 4 {
+		return errors.New("invalid size when reading key length")
+	}
+	val_len := make([]byte, 4)
+	s, err = r.Read(val_len)
+	if err != nil {
+		return err
+	}
+	if s != 4 {
+		return errors.New("invalid size when reading val length")
+	}
+	key_data := make([]byte, binary.LittleEndian.Uint32(key_len))
+	s, err = r.Read(key_data)
+	if err != nil {
+		return err
+	}
+	if s != int(binary.LittleEndian.Uint32(key_len)) {
+		return errors.New("invalid size when reading key data")
+	}
+	val_data := make([]byte, binary.LittleEndian.Uint32(val_len))
+	s, err = r.Read(val_data)
+	if err != nil {
+		return err
+	}
+	if s != int(binary.LittleEndian.Uint32(val_len)) {
+		return errors.New("invalid size when reading val data")
+	}
+	ent.key = key_data
+	ent.val = val_data
+	return nil
+}
 
 // QzBQWVJJOUhU https://trialofcode.org/