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1721. Swapping Nodes in a Linked List

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작성일 2022.04.04 21:56

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[Leetcode 시즌 3] 2022년 4월 4일 문제입니다.

[Medium] 1721. Swapping Nodes in a Linked List

You are given the head of a linked list, and an integer k.

Return the head of the linked list after swapping the values of the kth node from the beginning and the kth node from the end (the list is 1-indexed).

Example 1:

Input: head = [1,2,3,4,5], k = 2
Output: [1,4,3,2,5]

Example 2:

Input: head = [7,9,6,6,7,8,3,0,9,5], k = 5
Output: [7,9,6,6,8,7,3,0,9,5]

Constraints:

The number of nodes in the list is n.
1 <= k <= n <= 105
0 <= Node.val <= 100

#leetcode, #문제풀이, #medium, #facebook, #amazon, #Linked List, #Two Pointers, #시즌3

링크

https://leetcode.com/problems/swapping-nodes-in-a-linked-list/ 5000 회 연결

익명
작성일 2022.04.06 06:33

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
        swapNode = head
        fastNode = head
        
        for _ in range(k-1):
            fastNode = fastNode.next
            swapNode = swapNode.next
            
        slowNode = head
        while fastNode.next is not None:
            fastNode = fastNode.next
            slowNode = slowNode.next
        
        swapNode.val, slowNode.val= slowNode.val, swapNode.val
        
        return head

익명
작성일 2022.04.06 15:43

문제 풀이 감사합니다.

익명
작성일 2022.04.06 08:09

class Solution:
    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
        elements, current = [], head
        while current:
            elements.append(current)
            current = current.next
        if k > len(elements) // 2 + 1:
            k = len(elements) - k + 1
        elements[k - 1].val, elements[-k].val = elements[-k].val, elements[k - 1].val
        return head

익명
작성일 2022.04.06 15:44

문제 풀이 감사합니다.

익명
작성일 2022.04.06 23:30

class Solution {
public:
    ListNode* swapNodes(ListNode* head, int k) {
        int tmp;
        ListNode *backNode=NULL;
        ListNode *frontNode=NULL;
        ListNode *ListNodeTmp=head;
        int ListSize=0;

        while(ListNodeTmp!=NULL){
            ListSize++;
            if(ListSize==k){
                frontNode=ListNodeTmp;
            };
            ListNodeTmp=ListNodeTmp->next;
        };
        
        ListNodeTmp=head;
                
        for(int i=0;i<ListSize-k;i++){
            ListNodeTmp=ListNodeTmp->next;
        };
        
        backNode=ListNodeTmp;

        tmp=frontNode->val;
        frontNode->val=backNode->val;
        backNode->val=tmp;
        
        return head;
    };
};

익명
작성일 2022.04.14 20:28

class Solution {
    func swapNodes(_ head: ListNode?, _ k: Int) -> ListNode? {
        var node: ListNode? = head
        var count = 0
        var frontNode: ListNode?
        var backNode: ListNode?
        while true {
            count += 1
            if count == k {
                frontNode = node
            }
            
            if let next = node?.next {
                node = node?.next
            } else {
                break
            }
        }
        
        var back = count - k
        
        node = head
        while back > 0 {
            back -= 1
            node = node?.next
        }
        
        backNode = node
        
        guard frontNode != nil else { return nil }
        guard backNode != nil else { return nil }
        
        let val = frontNode!.val
        frontNode!.val = backNode!.val
        backNode!.val = val
        
        return head        
    }
}

익명
작성일 2022.04.17 13:18

class Solution:
    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
        p1, p2, idx, temp, idx2 = 0, 0, 0, head, 0
        while temp:
            if idx + 1 == k:
                p1 = temp
            idx += 1
            temp = temp.next
        temp = head
        while temp:
            if idx - (idx2) == k:
                p2 = temp
            idx2 += 1
            temp = temp.next
        p1.val, p2.val = p2.val, p1.val
        return head

익명
작성일 2022.08.13 13:41

package main

import "fmt"

type Node struct {
	val  int
	next *Node
}

type List struct {
	head *Node
	len  int
}

func (l *List) Insert(value int) {
	node := &Node{val: value, next: nil}
	if l.head == nil {
		l.head = node
		l.len += 1
	} else {
		x := l.head
		for x.next != nil {
			x = x.next
		}
		x.next = node
		l.len += 1
	}
}

func Show(l *List) {
	e := l.head
	for i := 0; i < l.len; i++ {
		fmt.Println(e.val)
		e = e.next
	}
}

func (l *List) Swap(idx int) {
	gIx := idx - 1
	tIx := l.len - gIx - 1
	e := l.head
	node := &Node{}

	for i := 0; i < l.len; i++ {
		if gIx == i {
			node = e
		}
		if tIx == i {
			e.val, node.val = node.val, e.val
		}
		e = e.next
	}
}

func main() {
	l := List{}
	for i := 1; i <= 5; i++ {
		l.Insert(i)
	}
	l.Swap(2)
	Show(&l)
}