我試圖解決 Go 中的 Leetcode 問題。問題是子集。這是我用一些調試日志編寫的整個代碼：package mainimport ( "fmt")func main() { v := []int{9, 0, 3, 5, 7} fmt.Println(subsets(v))}func subsets(nums []int) [][]int { result := [][]int{ []int{}, // empty } for _, num := range nums { fmt.Println("==========") fmt.Println(num) fmt.Printf("result = %v\n", result) temp := [][]int{} for _, r := range result { fmt.Printf("r = %v\n", r) temp = append(temp, append(r, num)) } for _, t := range temp { result = append(result, t) } fmt.Println("==========") } return result}（我還準備了Go play ground URL）這是上面代碼的輸出：==========9result = [[]]r = []====================0result = [[] [9]]r = []r = [9]====================3result = [[] [9] [0] [9 0]]r = []r = [9]r = [0]r = [9 0]====================5result = [[] [9] [0] [9 0] [3] [9 3] [0 3] [9 0 3]]r = []r = [9]r = [0]r = [9 0]r = [3]r = [9 3]r = [0 3]r = [9 0 3]====================7result = [[] [9] [0] [9 0] [3] [9 3] [0 3] [9 0 3] [5] [9 5] [0 5] [9 0 5] [3 5] [9 3 5] [0 3 5] [9 0 3 5]] // (a)r = []r = [9]r = [0]r = [9 0]r = [3]r = [9 3]r = [0 3]r = [9 0 3]r = [5]r = [9 5]r = [0 5]r = [9 0 5]r = [3 5]r = [9 3 5]r = [0 3 5]r = [9 0 3 7] // (b)==========[[] [9] [0] [9 0] [3] [9 3] [0 3] [9 0 3] [5] [9 5] [0 5] [9 0 5] [3 5] [9 3 5] [0 3 5] [9 0 3 7] [7] [9 7] [0 7] [9 0 7] [3 7] [9 3 7] [0 3 7] [9 0 3 7] [5 7] [9 5 7] [0 5 7] [9 0 5 7] [3 5 7] [9 3 5 7] [0 3 5 7] [9 0 3 7 7]]讓我們看看第5個result。（我在那里指出(a)）截至那里，最后一個元素result是[9, 0, 3, 5]，這是預期的行為。但是，在那之后，當我嘗試在 中寫入元素的調試日志時result，它會更改為[9, 0, 3, 7]( (b))。你知道為什么嗎？
1 回答
qq_花開花謝_0
TA貢獻1835條經驗 獲得超7個贊
append需要時更改r：而
不是：
temp = append(temp, append(r, num))
您可以使用：
rr := make([]int, len(r))
copy(rr, r)
rr = append(rr, num)
temp = append(temp, rr)
你很高興：
package main
import (
"fmt"
)
func main() {
v := []int{9, 0, 3, 5, 7}
fmt.Println(subsets(v))
}
func subsets(nums []int) [][]int {
result := [][]int{
[]int{}, // empty
}
for _, num := range nums {
fmt.Println("==========")
fmt.Println(num)
fmt.Printf("result = %v\n", result)
temp := [][]int{}
for _, r := range result {
fmt.Printf("r = %v\n", r)
// append(r, num)
rr := make([]int, len(r))
copy(rr, r)
rr = append(rr, num)
temp = append(temp, rr)
}
for _, t := range temp {
result = append(result, t)
}
fmt.Println("==========")
}
return result
}
只需調試您的代碼，您就會看到，它發生在這里：
temp := [][]int{}
for _, r := range result {
fmt.Println("result =", result, len(result), cap(result))
fmt.Println("r ==", r, len(r), cap(r))
fmt.Println("num =", num)
rr := append(r, num)
fmt.Println("r ==", r, len(r), cap(r))
fmt.Println("rr ==", rr, len(rr), cap(rr))
fmt.Println("result =", result, len(result), cap(result))
fmt.Println("temp =", temp)
temp = append(temp, rr)
fmt.Println("temp =", temp)
}
什么時候
result = [[] [9] [0] [9 0] [3] [9 3] [0 3] [9 0 3] [5] [9 5] [0 5] [9 0 5] [3 5] [9 3 5] [0 3 5] [9 0 3 5]] 16 16
r == [9 0 3] 3 4
num = 7
r == [9 0 3] 3 4
rr == [9 0 3 7] 4 4
result = [[] [9] [0] [9 0] [3] [9 3] [0 3] [9 0 3] [5] [9 5] [0 5] [9 0 5] [3 5] [9 3 5] [0 3 5] [9 0 3 7]] 16 16
因為：
append(r, num)
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