From 0e2cfbf69daa707c04070b80ede78ac4ef73d706 Mon Sep 17 00:00:00 2001
From: liuzhao <astroshot@outlook.com>
Date: Thu, 5 Jul 2018 21:38:37 +0800
Subject: [PATCH] stash

---
 test/leetcode/is_palindrome_list_test.go | 103 +++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 test/leetcode/is_palindrome_list_test.go

diff --git a/test/leetcode/is_palindrome_list_test.go b/test/leetcode/is_palindrome_list_test.go
new file mode 100644
index 0000000..5ad4873
--- /dev/null
+++ b/test/leetcode/is_palindrome_list_test.go
@@ -0,0 +1,103 @@
+package leetcode
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func toString(head *ListNode) string {
+	if head == nil {
+		fmt.Println("Empty ListNode")
+	}
+	str := ""
+	values := make([]string, 0, 50) // only for test
+
+	p := head
+	for p != nil {
+		values = append(values, fmt.Sprintf("%v", p.Val))
+		p = p.Next
+	}
+	str += strings.Join(values, ", ")
+	return str
+}
+
+func reverse(head *ListNode) *ListNode {
+	if head == nil {
+		return nil
+	}
+
+	var p, q, r *ListNode
+	p = head
+	q = nil
+	for p != nil {
+		r = q
+		q = p
+		p = p.Next
+		q.Next = r
+	}
+	return q
+}
+
+func buildListFromArray(arr []int) *ListNode {
+	var p, head *ListNode
+	p = nil
+	for _, value := range arr {
+		q := &ListNode{Val: value, Next: nil}
+		if p != nil {
+			p.Next = q
+		} else {
+			head = q
+		}
+		p = q
+	}
+	return head
+}
+
+func isPalindromeList(head *ListNode) bool {
+	if head == nil || head.Next == nil {
+		return true
+	}
+
+	fast := head
+	slow := head
+	for fast != nil {
+		slow = slow.Next
+		fast = fast.Next
+		if fast.Next != nil {
+			fast = fast.Next
+		} else {
+			// list contains even nodes
+
+		}
+	}
+	tail := reverse(slow)
+	p := head
+	for p != tail {
+		if p.Val != tail.Val {
+			return false
+		}
+		p = p.Next
+		tail = tail.Next
+	}
+	return true
+}
+
+func TestIsPalindromeList(t *testing.T) {
+	x := []int{1, 2, 3}
+	head := buildListFromArray(x)
+	str := toString(head)
+	assert.Equal(t, str, "1, 2, 3, 4")
+
+	tail := reverse(head)
+	str = toString(tail)
+	assert.Equal(t, str, "4, 3, 2, 1")
+
+}