Add solution for Challenge 2 by 4m4x #780
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WalkthroughA new Go solution file is added to challenge-2 that implements string reversal. The solution includes a Changes
Estimated code review effort🎯 2 (Simple) | ⏱️ ~8 minutes
Possibly related PRs
Pre-merge checks✅ Passed checks (3 passed)
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Actionable comments posted: 2
🧹 Nitpick comments (1)
challenge-2/submissions/4m4x/solution-template.go (1)
25-35: Consider a more efficient and idiomatic approach.The current implementation builds a slice of single-character strings and joins them, which is inefficient. Consider these alternatives:
- Reverse runes in place (most efficient):
func ReverseString(s string) string { runes := []rune(s) for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 { runes[i], runes[j] = runes[j], runes[i] } return string(runes) }
- Use strings.Builder (if you prefer the append approach):
func ReverseString(s string) string { runes := []rune(s) var builder strings.Builder builder.Grow(len(s)) for i := len(runes) - 1; i >= 0; i-- { builder.WriteRune(runes[i]) } return builder.String() }Also note:
- Line 29:
i >= 0is more idiomatic thani > -1- Line 33: Shadowing the parameter
sreduces clarity
| func main() { | ||
| // Read input from standard input | ||
| scanner := bufio.NewScanner(os.Stdin) | ||
| if scanner.Scan() { | ||
| input := scanner.Text() | ||
|
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||
| // Call the ReverseString function | ||
| output := ReverseString(input) | ||
|
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||
| // Print the result | ||
| fmt.Println(output) | ||
| } | ||
| } |
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Add error handling for scanner.
The code doesn't check for scanner errors after the scan operation. While scanner.Scan() returns false for both EOF and errors, you should check scanner.Err() to handle actual I/O errors properly.
Apply this diff to add 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.
| 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/4m4x/solution-template.go around lines 10 to 22, the
code calls scanner.Scan() but does not check scanner.Err() afterward; add error
handling by calling err := scanner.Err() after the scan (or after the scanning
loop), and if err != nil write a descriptive message to stderr (e.g.,
fmt.Fprintln(os.Stderr, "input error:", err)) and exit with a non-zero status
(os.Exit(1)) so actual I/O errors are surfaced instead of being ignored.
| for i := len(runes) - 1; i > -1; i-- { | ||
| output = append(output, string(s[i])) |
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Critical bug: incorrect indexing breaks Unicode support.
Line 30 uses s[i] (byte index) instead of runes[i] (rune index), which defeats the purpose of converting to runes on line 26. This will corrupt multi-byte UTF-8 characters like emoji or non-Latin scripts.
For example, reversing "Hello世界" would produce corrupted output because s[i] slices the original string byte-by-byte, splitting multi-byte UTF-8 sequences.
Apply this diff to fix the bug:
for i := len(runes) - 1; i > -1; i-- {
- output = append(output, string(s[i]))
+ output = append(output, string(runes[i]))
}📝 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.
| for i := len(runes) - 1; i > -1; i-- { | |
| output = append(output, string(s[i])) | |
| for i := len(runes) - 1; i > -1; i-- { | |
| output = append(output, string(runes[i])) | |
| } |
🤖 Prompt for AI Agents
In challenge-2/submissions/4m4x/solution-template.go around lines 29 to 30, the
loop currently appends string(s[i]) which indexes the original byte string and
corrupts multi-byte UTF-8 characters; change the append to use the rune slice
instead (append output with string(runes[i])) so each Unicode code point is
preserved when reversing, and remove any reliance on s[i] in this loop.
2 participants
Challenge 2 Solution
Submitted by: @4m4x
Challenge: Challenge 2
Description
This PR contains my solution for Challenge 2.
Changes
challenge-2/submissions/4m4x/solution-template.goTesting
Thank you for reviewing my submission! 🚀