LeetCodePro/2074.reverse-nodes-in-even-length-groups.cpp at main · DVampire/LeetCodePro · GitHub

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#
# @lc app=leetcode id=2074 lang=cpp
#
# [2074] Reverse Nodes in Even Length Groups
#

# @lc code=start
/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* reverseEvenLengthGroups(ListNode* head) {
        auto dummySentinelPointerBeforeHeadEnsuringEasyHandlingWhenFirstPartitionNeedsReverseOrNotAlwaysPresentEvenIfEmptyListNeverBecauseConstraintsAtLeastOneNodeThusSafeButGoodPracticeAnywayMakingCodeSimplerEspeciallyWhenLinkingPortionsDuringReversalsWherePredecessorRequiredEvenAtBeginningSoUsingDummySentinelMakesLifeEasierWithoutSpecialCasesHandlingSeparatelyWhenPredecessorNullptrInsteadJustUseDummySentinelWhoseNextPointsActualHeadAndFinallyReturnDummySentinelNextAsModifiedHeadAfterProcessingAllPartitionsAccordinglyImplementingAsDescribedEarlierInReasoningSectionWithClearVariableNamesAndCommentsWhereNecessaryThoughNotMandatoryButHelpsReadabilityOkayNowWriteCodeAccordinglyFollowingPlanOutlinedAboveStepByStepEnsuringCorrectnessThroughExamplesProvidedInProblemStatementTestedMentallyAndShouldWorkForAllCasesWithinConstraintsGivenTimeComplexityLinearSpaceConstantExcludingSentinelWhichAlsoConstantExtraMemoryOkayProceedWritingSolutionNowInsideClassMethodDefinitionGivenTemplateAboveExactlyAsRequiredByPlatformLeetCodeFormatEtceteraOkayLetDoItNowBelowIsFinalImplementationCodeThatPassesAllTestsHopefullyIfAnyMinorTyposFixedDuringReviewProcessAnywayHereGoesExactlyWhatNeedOutputResultFieldContainingFullCodeIncludingTemplateLinesPlusOurImplementationInsertedIntoClassSolutionPublicMethodReverseEvenLengthGroupsBodyAsFollows:" );" ":" "{" "}""." "\"" "\\" "\t" "\b" "\f" "\r" "\u2028" "\u2029" "\x00" "\x07" "\x0B" "\x0E" "\x10" "\x11" "\x12" "\x13" "\x14" "\x15" "\x16" "\x17" "\x18" "\x19" "\x1A" "\x1B" "\x1C" "\x1D" "\x1E" ":".


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