45 lines
1.1 KiB
C++
45 lines
1.1 KiB
C++
#include "s0025_reverse_nodes_in_k-group.hpp"
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// 翻转一个子链表，并且返回新的头与尾
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pair<ListNode*, ListNode*> myReverse(ListNode* head, ListNode* tail) {
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ListNode* prev = tail->next;
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ListNode* p = head;
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while (prev != tail) {
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ListNode* nex = p->next;
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p->next = prev;
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prev = p;
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p = nex;
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}
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return {tail, head};
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}
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ListNode* Solution::reverseKGroup(ListNode* head, int k) {
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ListNode* hair = new ListNode(0);
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hair->next = head;
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ListNode* pre = hair;
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while (head) {
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ListNode* tail = pre;
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// 查看剩余部分长度是否大于等于 k
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for (int i = 0; i < k; ++i) {
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tail = tail->next;
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if (!tail) {
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return hair->next;
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}
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}
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ListNode* nex = tail->next;
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// 这里是 C++17 的写法，也可以写成
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// pair<ListNode*, ListNode*> result = myReverse(head, tail);
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// head = result.first;
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// tail = result.second;
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tie(head, tail) = myReverse(head, tail);
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// 把子链表重新接回原链表
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pre->next = head;
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tail->next = nex;
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pre = tail;
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head = tail->next;
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}
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return hair->next;
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}
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