234. 回文链表

.gitignore

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+/.idea

main.go

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+package main
+
+import "fmt"
+
+// ListNode Definition for singly-linked list.
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func isPalindrome(head *ListNode) bool {
+	srcHead := head
+	head = head.Next
+	// var left, right *ListNode
+	cnt := 1
+	for head != nil {
+		head = head.Next
+		cnt++
+	}
+	head = srcHead.Next
+	lastNode := srcHead
+	srcHead.Next = nil
+	half := cnt / 2
+	half--
+	for range half {
+		p := head.Next
+		head.Next = lastNode
+		lastNode = head
+		head = p
+	}
+	if cnt&1 == 1 {
+		head = head.Next
+	}
+	for head != nil && lastNode != nil {
+		if head.Val != lastNode.Val {
+			return false
+		}
+		head = head.Next
+		lastNode = lastNode.Next
+	}
+	if head != nil || lastNode != nil {
+		return false
+	}
+	return true
+}
+
+func main() {
+	isPalindrome := isPalindrome(&ListNode{
+		Val: 1,
+		Next: &ListNode{
+			Val: 2,
+		},
+	})
+	fmt.Printf("isPalindrome: %v\n", isPalindrome)
+}