Commit871212d

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Create 20-206. Reverse Linked List

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	`1`	`+Iterative Solution:`
	`2`	`+class Solution:`
	`3`	`+ def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:`
	`4`	`+ prev, curr = None, head`
	`5`	`+`
	`6`	`+ while curr:`
	`7`	`+ nxt = curr.next # save next`
	`8`	`+ curr.next = prev # add prev element to current's next`
	`9`	`+ prev = curr # increment prev`
	`10`	`+ curr = nxt # increment curr`
	`11`	`+ return prev # curr will be at NULL and prev will be the last node\`
	`12`	`+`
	`13`	`+`
	`14`	`+`
	`15`	`+Recursive Solution:`
	`16`	`+class Solution:`
	`17`	`+ def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:`
	`18`	`+`
	`19`	`+ def recursion(prev, curr):`
	`20`	`+ if not curr:`
	`21`	`+ return prev`
	`22`	`+`
	`23`	`+ tail = recursion(curr, curr.next)`
	`24`	`+ curr.next = prev`
	`25`	`+`
	`26`	`+ return tail`
	`27`	`+`
	`28`	`+ return recursion(None, head)`

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