u

2026-06-21 13:11:31 +10:00
parent 3bce899398
commit 35c362681e
6 changed files with 533 additions and 0 deletions
@@ -0,0 +1,135 @@
+package top100liked
+
+import (
+	"fmt"
+	"testing"
+)
+
+// https://leetcode.cn/problems/reverse-nodes-in-k-group/description/?envType=study-plan-v2&envId=top-100-liked
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+// 提交记录 3
+// 你就说快不快吧
+// func reverseKGroup(head *ListNode, k int) *ListNode {
+// 	if k == 1 {
+// 		return head
+// 	}
+// 	nodes := []*ListNode{}
+// 	p := head
+// 	nodes = append(nodes, &ListNode{0, head})
+// 	for p != nil {
+// 		nodes = append(nodes, p)
+// 		p = p.Next
+// 	}
+// 	tmp := nodes[0]
+// 	for i := range (len(nodes) - 1) / k {
+// 		tmp.Next = nodes[(i+1)*k]
+// 		nodes[i*k+1].Next = nodes[(i+1)*k].Next
+// 		for j := range k - 1 {
+// 			nodes[(i+1)*k-j].Next = nodes[(i+1)*k-j-1]
+// 		}
+// 		tmp = nodes[i*k+1]
+// 	}
+// 	return nodes[0].Next
+// }
+
+func reverseKGroup(head *ListNode, k int) *ListNode {
+	dummy := &ListNode{Next: head}
+	prev := dummy
+	for {
+		// 检查剩余节点是否够 k 个
+		tail := prev
+		for range k {
+			tail = tail.Next
+			if tail == nil {
+				return dummy.Next
+			}
+		}
+		next := tail.Next // 下一组的起点
+		// 翻转 [prev, tail] 这 k 个节点
+		p := prev.Next
+		var reversedHead, reversedTail *ListNode
+		reversedTail = p // 翻转后 p 变成尾部
+		var pre *ListNode
+		for range k {
+			tmp := p.Next
+			p.Next = pre
+			pre = p
+			p = tmp
+		}
+		reversedHead = pre
+		// 接回原链表
+		prev.Next = reversedHead
+		reversedTail.Next = next
+		prev = reversedTail
+	}
+}
+
+func Test1(t *testing.T) {
+	input := &ListNode{
+		Val: 1,
+		Next: &ListNode{
+			Val: 2,
+			Next: &ListNode{
+				Val: 3,
+				Next: &ListNode{
+					Val: 4,
+					Next: &ListNode{
+						Val:  5,
+						Next: nil,
+					},
+				},
+			},
+		},
+	}
+	output := reverseKGroup(input, 2)
+	for output != nil {
+		fmt.Print(output.Val, " ")
+		output = output.Next
+	}
+}
+
+func Test2(t *testing.T) {
+	input := &ListNode{
+		Val: 1,
+		Next: &ListNode{
+			Val: 2,
+			Next: &ListNode{
+				Val: 3,
+				Next: &ListNode{
+					Val: 4,
+					Next: &ListNode{
+						Val:  5,
+						Next: nil,
+					},
+				},
+			},
+		},
+	}
+	output := reverseKGroup(input, 3)
+	for output != nil {
+		fmt.Print(output.Val, " ")
+		output = output.Next
+	}
+	fmt.Println()
+}
+
+func Test3(t *testing.T) {
+	input := &ListNode{
+		Val: 1,
+		Next: &ListNode{
+			Val:  2,
+			Next: nil,
+		},
+	}
+	output := reverseKGroup(input, 2)
+	for output != nil {
+		fmt.Print(output.Val, " ")
+		output = output.Next
+	}
+	fmt.Println()
+}