func SumLinkedListsReverse(l1, l2 *linkedlist.LinkedList) *linkedlist.LinkedList {
l1.Reverse()
l2.Reverse()
result := SumLinkedLists(l1, l2)
result.Reverse()
return result
}
func PartitionLinkedList(l *linkedlist.LinkedList, x int) {
var ltroot, lessthan, gtroot, greaterthan *linkedlist.Node
current := l.Root
for current != nil {
if current.Value < x {
if ltroot == nil || lessthan == nil {
ltroot = current
lessthan = current
} else {
lessthan.Next = current
lessthan = lessthan.Next
}
} else {
if gtroot == nil || greaterthan == nil {
gtroot = current
greaterthan = current
} else {
greaterthan.Next = current
greaterthan = greaterthan.Next
}
}
current = current.Next
}
if l.Root != nil {
if ltroot != nil && gtroot != nil {
l.Root = ltroot
l.Head = greaterthan
lessthan.Next = gtroot
greaterthan.Next = nil
}
}
}
// O(n^2)
func RemoveDuplicatesNoStruct(l *linkedlist.LinkedList) {
var prev *linkedlist.Node
cur := l.Root
for cur != nil {
// for each node we need to iterate through the
// list and delete all duplicates ahead of it
RemoveDuplicatesHelper(cur, l, cur.Value)
prev = cur
cur = cur.Next
}
if prev != nil {
l.Head = prev
}
}
func RemoveDuplicates(l *linkedlist.LinkedList) {
if l.Length == 0 {
return
}
used := make(map[int]bool, l.Length)
prev := l.Root
cur := prev.Next
used[prev.Value] = true
for cur != nil {
if _, dupe := used[cur.Value]; dupe {
prev.Next = cur.Next
cur = cur.Next
l.Length--
} else {
used[cur.Value] = true
prev = cur
cur = cur.Next
}
}
l.Head = prev
}
