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Reverse a Linked List

Easy

Three pointers, one flipped link per step. The whole trick is saving the next node before you overwrite it.

three pointersin place
TimeO(n)
SpaceO(1)
InputNode values in order
cur
1
→
2
→
3
→
4
→
5
→ null

Start with prev as null and cur at the head.

flips0
1 / 17
prev = null; cur = head
while cur:
nxt = cur.next // save it first
cur.next = prev // flip the link
prev = cur
cur = nxt
return prev
Why it matters

Every list problem that rewires pointers is a variation of this loop.

Practise this
Reverse Linked ListEReverse Nodes in k-GroupHReorder ListMPalindrome Linked ListE
Keyboard
space play← → stepr restartctrl K search

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