u

2026-06-21 13:11:31 +10:00
parent 3bce899398
commit 35c362681e
6 changed files with 533 additions and 0 deletions
@@ -0,0 +1,89 @@
+package top100liked
+
+import (
+	"fmt"
+	"testing"
+)
+
+// https://leetcode.cn/problems/swap-nodes-in-pairs/description/?envType=study-plan-v2&envId=top-100-liked
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func swapPairs(head *ListNode) *ListNode {
+	if head == nil {
+		return nil
+	}
+	if head.Next == nil {
+		return head
+	}
+	dummy := &ListNode{0, head}
+	p1, p2, p3 := dummy, dummy.Next, dummy.Next.Next
+	for {
+		p1.Next = p3
+		p2.Next = p3.Next
+		p3.Next = p2
+		p2, p3 = p3, p2
+		for range 2 {
+			if p3.Next == nil {
+				return dummy.Next
+			}
+			p1 = p1.Next
+			p2 = p2.Next
+			p3 = p3.Next
+		}
+	}
+}
+
+// func swapPairs(head *ListNode) *ListNode {
+//     dummyHead := &ListNode{0, head}
+//     temp := dummyHead
+//     for temp.Next != nil && temp.Next.Next != nil {
+//         node1 := temp.Next
+//         node2 := temp.Next.Next
+//         temp.Next = node2
+//         node1.Next = node2.Next
+//         node2.Next = node1
+//         temp = node1
+//     }
+//     return dummyHead.Next
+// }
+
+func Test(t *testing.T) {
+	input1 := &ListNode{
+		Val: 1,
+		Next: &ListNode{
+			Val: 2,
+			Next: &ListNode{
+				Val: 3,
+				Next: &ListNode{
+					Val:  4,
+					Next: nil,
+				},
+			},
+		},
+	}
+	input2 := &ListNode{
+		Val: 1,
+		Next: &ListNode{
+			Val: 2,
+			Next: &ListNode{
+				Val:  3,
+				Next: nil,
+			},
+		},
+	}
+	output := swapPairs(input1)
+	for output != nil {
+		fmt.Print(output.Val, " ")
+		output = output.Next
+	}
+	fmt.Println()
+	output = swapPairs(input2)
+	for output != nil {
+		fmt.Print(output.Val, " ")
+		output = output.Next
+	}
+}