148. 排序链表

main.go

@@ -1,78 +1,62 @@
 package main
 
-import "fmt"
-
-/**
- * Definition for singly-linked list.*/
-type ListNode struct {
-	Val  int
-	Next *ListNode
-}
-
-func makeLink(arr []int) *ListNode {
-	if len(arr) == 0 {
-		return nil
-	}
-	head := &ListNode{}
-	cur := head
-	for _, v := range arr {
-		cur.Next = &ListNode{Val: v}
-		cur = cur.Next
-	}
-	return head.Next
-}
-func checkLink(head *ListNode) {
-	for head != nil {
-		fmt.Println(head.Val)
-		head = head.Next
-	}
-}
-
-func reverseBetween(head *ListNode, left int, right int) *ListNode {
-	if head.Next == nil {
+func conquerAndSort(head *ListNode, end *ListNode) *ListNode {
+	if head == nil || head == end || head.Next == nil {
 		return head
 	}
-	left--
-	right--
-	cur_idx := 0
-	cur := head
-	var left_node *ListNode
-	var left_pre_node *ListNode = nil
-	_ = left_pre_node
-	var last_node *ListNode = nil
-	do_rev := false
-
-	for {
-		if cur_idx == left {
-			left_node = cur
-			left_pre_node = last_node
-			do_rev = true
-		}
-		next := cur.Next
-		if do_rev {
-			next = cur.Next
-			cur.Next = last_node
-			if cur_idx == right {
-				left_node.Next = next
-				if left_pre_node != nil {
-					left_pre_node.Next = cur
-				} else {
-					head = cur
-				}
-				do_rev = false
+	if head.Next == end {
+		if end != nil {
+			if head.Val > end.Val {
+				head.Val, end.Val = end.Val, head.Val
 			}
 		}
-		last_node = cur
-		cur = next
-		cur_idx++
-		if cur == nil {
-			break
+		return head
+	}
+	if head.Next.Next == end {
+		if head.Val > head.Next.Val {
+			head.Next.Val, head.Val = head.Val, head.Next.Val
 		}
+		return head
+	}
+	slow, fast := head, head
+	for fast.Next != nil && fast.Next.Next != nil {
+		slow = slow.Next
+		fast = fast.Next.Next
+	}
+	lastSlow := slow
+	slow = slow.Next
+	lastSlow.Next = nil
+	a := conquerAndSort(head, nil)
+	b := conquerAndSort(slow, end)
+	if a.Val > b.Val {
+		a, b = b, a
+	}
+	// a Val < b Val
+	head = a
+	cur := a
+	a = a.Next
+	for a != nil && b != nil {
+		if a.Val > b.Val {
+			cur.Next = b
+			b = b.Next
+		} else {
+			cur.Next = a
+			a = a.Next
+		}
+		cur = cur.Next
+	}
+	if a == nil {
+		cur.Next = b
+	} else {
+		cur.Next = a
 	}
 	return head
 }
+func sortList(head *ListNode) *ListNode {
+	return conquerAndSort(head, nil)
+}
 
 func main() {
-	arr := []int{3, 5}
-	checkLink(reverseBetween(makeLink(arr), 1, 2))
+	arr := []int{-1, 5, 3, 4, 0}
+	checkLink(sortList(makeLink(arr)))
 }