如何在golang中迭代相同的列表时从列表中删除元素

Question

我是新来的语言.我希望在根据go语言中的条件迭代列表时从列表中删除元素.例如,我想从列表中删除重复的元素.代码如下.

package main
import (
    "container/list"
    "fmt"
)
var sMap map[int]bool
func main() {
    l := list.New()
    l.PushFront(4)
    l.PushFront(5)
    l.PushFront(7)
    l.PushFront(6)
    l.PushFront(5)
    l.PushFront(4)
    l.PushFront(5)
    l.PushFront(7)
    l.PushBack(9)
    l = removeDuplicate(l)
    for e := l.Front(); e != nil; e = e.Next() {
        fmt.Println(e.Value)
    }
}
func removeDuplicate(l *list.List) *list.List {
    sMap = make(map[int]bool)
    for e := l.Front(); e != nil; e = e.Next() {
        m := e.Value.(int)
        fmt.Println("VALUE : ", m)
        if sMap[m] == true {
            fmt.Println("Deleting ", e.Value)
            l.Remove(e)
        } else {
            fmt.Println("Adding New Entry", e.Value)
            sMap[m] = true
        }
    }
    return l
}

上面的代码只遍历列表,直到第一次删除.我试图在迭代相同的列表时删除元素.这就是它无法正常工作的原因.有人可以在golang中建议列表迭代器吗？

Answer 1

如果e从列表中删除,e.Next()则将返回下一循环中的call nil.因此,需要分配e.Next()给next删除之前e.以下是通过迭代清除所有元素的示例(在list_test.go中)

// Clear all elements by iterating
var next *Element
for e := l.Front(); e != nil; e = next {
    next = e.Next()
    l.Remove(e)
}

可以将相同的模式应用于以下问题;

package main
import (
    "container/list"
    "fmt"
)
var sMap map[int]bool
func main() {
    l := list.New()
    l.PushFront(4)
    l.PushFront(5)
    l.PushFront(7)
    l.PushFront(6)
    l.PushFront(5)
    l.PushFront(4)
    l.PushFront(5)
    l.PushFront(7)
    l.PushBack(9)
    l = removeDuplicate(l)
    for e := l.Front(); e != nil; e = e.Next() {
        fmt.Println(e.Value)
    }
}
func removeDuplicate(l *list.List) *list.List {
    sMap = make(map[int]bool)
    var next *list.Element
    for e := l.Front(); e != nil; e = next {
        m := e.Value.(int)
        next = e.Next()
        fmt.Println("VALUE : ", m)
        if sMap[m] == true {
            fmt.Println("Deleting ", e.Value)
            l.Remove(e)
        } else {
            fmt.Println("Adding New Entry", e.Value)
            sMap[m] = true
        }
    }
    return l
}

产量

VALUE :  7
Adding New Entry 7
VALUE :  5
Adding New Entry 5
VALUE :  4
Adding New Entry 4
VALUE :  5
Deleting  5
VALUE :  6
Adding New Entry 6
VALUE :  7
Deleting  7
VALUE :  5
Deleting  5
VALUE :  4
Deleting  4
VALUE :  9
Adding New Entry 9
7
5
4
6
9