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Merged
RezaSi merged 1 commit into from
Dec 6, 2025
Merged

Add solution for Challenge 2 by DaniilYuz #843

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30 changes: 30 additions & 0 deletions challenge-2/submissions/DaniilYuz/solution-template.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
package main

import (
"bufio"
"fmt"
"os"
)

func main() {
// Read input from standard input
scanner := bufio.NewScanner(os.Stdin)
if scanner.Scan() {
input := scanner.Text()

// Call the ReverseString function
output := ReverseString(input)

// Print the result
fmt.Println(output)
}
}
Comment on lines +9 to +21
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@coderabbitai coderabbitai bot Dec 6, 2025

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⚠️ Potential issue | 🟠 Major

Add error handling for scanner.

The code doesn't check scanner.Err() after scanning. If an I/O error occurs while reading from stdin, it will be silently ignored, which could lead to unexpected behavior or silent failures.

Apply this diff to add proper error handling:

 func main() {
 	// Read input from standard input
 	scanner := bufio.NewScanner(os.Stdin)
 	if scanner.Scan() {
 		input := scanner.Text()
 
 		// Call the ReverseString function
 		output := ReverseString(input)
 
 		// Print the result
 		fmt.Println(output)
 	}
+	if err := scanner.Err(); err != nil {
+		fmt.Fprintf(os.Stderr, "Error reading input: %v\n", err)
+		os.Exit(1)
+	}
 }
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
func main() {
// Read input from standard input
scanner := bufio.NewScanner(os.Stdin)
if scanner.Scan() {
input := scanner.Text()
// Call the ReverseString function
output := ReverseString(input)
// Print the result
fmt.Println(output)
}
}
func main() {
// Read input from standard input
scanner := bufio.NewScanner(os.Stdin)
if scanner.Scan() {
input := scanner.Text()
// Call the ReverseString function
output := ReverseString(input)
// Print the result
fmt.Println(output)
}
if err := scanner.Err(); err != nil {
fmt.Fprintf(os.Stderr, "Error reading input: %v\n", err)
os.Exit(1)
}
}
🤖 Prompt for AI Agents 
In challenge-2/submissions/DaniilYuz/solution-template.go around lines 9 to 21,
the scanner error is not checked after scanning which can silently ignore I/O
problems; after the Scan() block call scanner.Err(), and if it returns a non-nil
error write a descriptive message to stderr (using fmt.Fprintln(os.Stderr, ...))
and exit with a non-zero status (os.Exit(1)) or return, otherwise continue to
call ReverseString and print the output; ensure the error check runs after the
Scan() completes so genuine read errors are handled.


// ReverseString returns the reversed string of s.
func ReverseString(s string) string {
res := []byte(s)
for i, j := 0, len(res)-1; i < j; i, j = i+1, j-1 {
res[i], res[j] = res[j], res[i]
}
return string(res)
}
Comment on lines +24 to +30
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@coderabbitai coderabbitai bot Dec 6, 2025

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⚠️ Potential issue | 🔴 Critical

Fix Unicode handling in ReverseString.

The function uses []byte(s) which reverses individual bytes. This breaks multi-byte UTF-8 characters like emojis, Chinese/Arabic/Cyrillic text, etc. For example, reversing "Hello 世界" would corrupt the Chinese characters since each character spans multiple bytes.

Apply this diff to handle Unicode correctly:

 // ReverseString returns the reversed string of s.
 func ReverseString(s string) string {
-	res := []byte(s)
+	res := []rune(s)
 	for i, j := 0, len(res)-1; i < j; i, j = i+1, j-1 {
 	    res[i], res[j] = res[j], res[i] 
 	}
 	return string(res)
 }
🤖 Prompt for AI Agents 
In challenge-2/submissions/DaniilYuz/solution-template.go around lines 24 to 30,
the function reverses bytes using []byte(s) which corrupts multi-byte UTF-8
characters; convert the string to a []rune, reverse the rune slice in-place
(swap runes from ends moving inward), and return string(runes) so Unicode
characters are preserved while keeping the same function signature and behavior.

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