leetcode 61. Rotate List和86. Partition List

目录

61. Rotate List

 86. Partition List

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61. Rotate List

代码：

/*** 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* rotateRight(ListNode* head, int k) {if(head == nullptr)return head;if(k == 0)return head;ListNode* cur = head;int count = 0;while(cur){count++;cur = cur->next;}k = k%count;if(k == 0)return head;ListNode *pre = nullptr;cur = head;for(int i = 0;i < count -k;i++){pre = cur;cur = cur->next;}if(pre ==nullptr)return head;pre->next = nullptr;ListNode* newhead = cur;while(cur->next){cur = cur->next;}cur->next = head;return newhead;}
};

 86. Partition List

代码：

/*** 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* partition(ListNode* head, int x) {if(head == nullptr)return nullptr;ListNode* left_dummy = new ListNode(-1,nullptr);ListNode* right_dummy =new ListNode(-1,nullptr);ListNode* leftpre = left_dummy;ListNode* rightpre = right_dummy;ListNode* cur = head;while(cur){if(cur->val < x){leftpre->next = cur;leftpre = cur;}else{rightpre->next = cur;rightpre = cur;}cur = cur->next;}leftpre->next = right_dummy->next;rightpre->next = nullptr;ListNode* ans = left_dummy->next;delete left_dummy;delete right_dummy;return ans;}
};