I am new to go language. I would like to remove elements from the list while iterating the list based on a condition in go language. For example I want remove the duplicate elements from the list. Code is given below.
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
}
The above code iterates through the list only till the first removal. I am trying to remove the element while iterating through the same list. That is the reason why it is not working. Could anyone suggest an list iterator in golang?
If e
is removed from the list then call of e.Next()
in the next loop will return nil
. Therefore, need to assign e.Next()
to the next
before deleting e
. Here is the example to clear all elements by iterating (in list_test.go)
// Clear all elements by iterating
var next *Element
for e := l.Front(); e != nil; e = next {
next = e.Next()
l.Remove(e)
}
Same pattern can be applied to the question as following;
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
}
Output
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