54 lines
1.6 KiB
C++
54 lines
1.6 KiB
C++
// Source : https://leetcode.com/problems/odd-even-linked-list/
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// Author : Hao Chen
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// Date : 2016-01-16
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/***************************************************************************************
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*
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* Given a singly linked list, group all odd nodes together followed by the even nodes.
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* Please note here we are talking about the node number and not the value in the nodes.
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*
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* You should try to do it in place. The program should run in O(1) space complexity
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* and O(nodes) time complexity.
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*
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* Example:
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* Given 1->2->3->4->5->NULL,
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* return 1->3->5->2->4->NULL.
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*
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* Note:
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* The relative order inside both the even and odd groups should remain as it was in
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* the input.
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* The first node is considered odd, the second node even and so on ...
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*
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* Credits:Special thanks to @aadarshjajodia for adding this problem and creating all
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* test cases.
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***************************************************************************************/
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/**
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* Definition for singly-linked list.
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* struct ListNode {
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* int val;
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* ListNode *next;
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* ListNode(int x) : val(x), next(NULL) {}
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* };
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*/
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class Solution {
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public:
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ListNode* oddEvenList(ListNode* head) {
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if (!head) return head;
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ListNode* pOdd = head;
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ListNode* p = head->next;
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ListNode* pNext = NULL;
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while(p && (pNext=p->next)) {
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p->next = pNext->next;
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pNext->next = pOdd->next;
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pOdd->next = pNext;
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p = p->next;
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pOdd = pOdd->next;
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}
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return head;
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}
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};
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