136 lines
2.4 KiB
Go
136 lines
2.4 KiB
Go
package top100liked
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import (
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"fmt"
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"testing"
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)
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// https://leetcode.cn/problems/reverse-nodes-in-k-group/description/?envType=study-plan-v2&envId=top-100-liked
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type ListNode struct {
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Val int
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Next *ListNode
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}
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// 提交记录 3
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// 你就说快不快吧
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// func reverseKGroup(head *ListNode, k int) *ListNode {
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// if k == 1 {
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// return head
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// }
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// nodes := []*ListNode{}
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// p := head
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// nodes = append(nodes, &ListNode{0, head})
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// for p != nil {
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// nodes = append(nodes, p)
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// p = p.Next
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// }
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// tmp := nodes[0]
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// for i := range (len(nodes) - 1) / k {
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// tmp.Next = nodes[(i+1)*k]
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// nodes[i*k+1].Next = nodes[(i+1)*k].Next
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// for j := range k - 1 {
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// nodes[(i+1)*k-j].Next = nodes[(i+1)*k-j-1]
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// }
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// tmp = nodes[i*k+1]
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// }
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// return nodes[0].Next
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// }
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func reverseKGroup(head *ListNode, k int) *ListNode {
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dummy := &ListNode{Next: head}
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prev := dummy
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for {
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// 检查剩余节点是否够 k 个
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tail := prev
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for range k {
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tail = tail.Next
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if tail == nil {
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return dummy.Next
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}
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}
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next := tail.Next // 下一组的起点
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// 翻转 [prev, tail] 这 k 个节点
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p := prev.Next
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var reversedHead, reversedTail *ListNode
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reversedTail = p // 翻转后 p 变成尾部
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var pre *ListNode
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for range k {
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tmp := p.Next
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p.Next = pre
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pre = p
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p = tmp
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}
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reversedHead = pre
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// 接回原链表
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prev.Next = reversedHead
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reversedTail.Next = next
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prev = reversedTail
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}
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}
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func Test1(t *testing.T) {
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input := &ListNode{
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Val: 1,
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Next: &ListNode{
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Val: 2,
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Next: &ListNode{
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Val: 3,
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Next: &ListNode{
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Val: 4,
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Next: &ListNode{
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Val: 5,
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Next: nil,
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},
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},
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},
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},
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}
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output := reverseKGroup(input, 2)
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for output != nil {
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fmt.Print(output.Val, " ")
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output = output.Next
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}
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}
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func Test2(t *testing.T) {
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input := &ListNode{
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Val: 1,
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Next: &ListNode{
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Val: 2,
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Next: &ListNode{
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Val: 3,
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Next: &ListNode{
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Val: 4,
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Next: &ListNode{
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Val: 5,
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Next: nil,
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},
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},
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},
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},
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}
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output := reverseKGroup(input, 3)
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for output != nil {
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fmt.Print(output.Val, " ")
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output = output.Next
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}
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fmt.Println()
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}
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func Test3(t *testing.T) {
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input := &ListNode{
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Val: 1,
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Next: &ListNode{
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Val: 2,
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Next: nil,
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},
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}
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output := reverseKGroup(input, 2)
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for output != nil {
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fmt.Print(output.Val, " ")
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output = output.Next
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}
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fmt.Println()
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}
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