英文:
Misuse of slices in Go
问题
我正在编写一些代码来查找字符串中的所有回文串：
func palindrome(s string) bool {for i, j := 0, len(s) - 1; i < j; i, j = i + 1, j - 1 {if s[i] != s[j] {return false}}return true}func dfs(s string, start int, sol *[][]string, curr *[]string) {if start == len(s) {*sol = append(*sol, *curr)fmt.Println("中间值：", *sol)return}for i := start + 1; i <= len(s); i++ {substr := s[start:i]if palindrome(substr) {*curr = append(*curr, substr)dfs(s, i, sol, curr)*curr = (*curr)[:len(*curr) - 1]}}}func main() {sol := [][]string{}dfs("aab", 0, &sol, new([]string))fmt.Println("最终值：", sol)}
程序输出：
中间值： [[a a b]]中间值： [[aa b b] [aa b]]最终值： [[aa b b] [aa b]]
看起来当函数 dfs() 返回时，sol 被破坏了，它的第一个元素从 [a a b] 变成了 [aa b b]。
我无法弄清楚我在声明和使用参数 sol 和 curr 方面出了什么问题。
英文:
I'm working on some code to find all palindromes from a string:
func palindrome(s string) bool {for i, j := 0, len(s) - 1; i < j; i, j = i + 1, j - 1 {if s[i] != s[j] {return false}}return true}func dfs(s string, start int, sol *[][]string, curr *[]string) {if start == len(s) {*sol = append(*sol, *curr)fmt.Println("intermediate value:", *sol)return}for i := start + 1; i <= len(s); i++ {substr := s[start:i]if palindrome(substr) {*curr = append(*curr, substr)dfs(s, i, sol, curr)*curr = (*curr)[:len(*curr) - 1]}}}func main() {sol := [][]string{}dfs("aab", 0, &sol, new([]string))fmt.Println("last value:", sol)}
The program outputs:
intermediate value: [[a a b]]intermediate value: [[aa b b] [aa b]]last value: [[aa b b] [aa b]]
Looks like when function dfs() returns, sol gets corrupted and its first element changes from [a a b] to [aa b b].
I can't figure out what's wrong with how I declare and use parameters sol and curr.
答案1
得分: 1
根据JimB和Ricardo Souza发布的评论，修复方法是在更新*sol时需要额外添加一个append：
*sol = append(*sol, append([]string{}, (*curr)...))
这段代码的改动会复制*curr的内容。
另外，curr不需要是指针类型。
英文:
From the comments posted by JimB and Ricardo Souza, the fix is an extra append needed when updating *sol:
*sol = append(*sol, append([]string{}, (*curr)...))
This code change makes a copy of the contents of *curr.
Also, curr doesn't need to be a pointer type.
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