36 lines
868 B
C++
36 lines
868 B
C++
#include <algorithm>
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/**
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* Definition for singly-linked list.
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*/
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struct ListNode {
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int val;
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ListNode* next;
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explicit ListNode(int x, ListNode* n = nullptr) : val(x), next(n) {}
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~ListNode() { delete this->next; this->next = nullptr; }
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};
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/**
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* 1721. Swapping Nodes in a Linked List
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* You are given the head of a linked list, and an integer k.
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* 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).
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*/
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class Solution {
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public:
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static ListNode* swapNodes(ListNode* head, int k) {
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if (!head || !head->next) return head;
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auto* fast = head;
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for (int i = 1; i < k; ++i)
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fast = fast->next;
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auto* slow = head;
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auto* S1 = fast;
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while (fast->next) {
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fast = fast->next;
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slow = slow->next;
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}
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std::swap(slow->val, S1->val);
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return head;
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}
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};
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