add 'Rotate List'

tags/linked-list/rotateList/main.go

@@ -0,0 +1,122 @@
+package main
+
+import "fmt"
+
+func main() {
+	var vals []int
+	var k int
+
+	//vals = []int{1, 2, 3, 4, 5}
+	//k = 8
+	//printList(rotateRight(createList(vals), k))
+	//return
+
+	vals = []int{}
+	k = 1
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1}
+	k = 1
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1}
+	k = 2
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 1
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 2
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 3
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 4
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 5
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 6
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 7
+	printList(rotateRight(createList(vals), k))
+
+	vals = []int{1, 2, 3, 4, 5}
+	k = 8
+	printList(rotateRight(createList(vals), k))
+}
+
+//Definition for singly-linked list.
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func createList(vals []int) *ListNode {
+	var head, list *ListNode
+	for _, v := range vals {
+		if head == nil {
+			list = &ListNode{Val: v, Next: nil}
+			head = list
+			continue
+		}
+		var temp = &ListNode{Val: v, Next: nil}
+		list.Next = temp
+		list = list.Next
+	}
+	return head
+}
+
+func printList(node *ListNode) {
+	var temp = node
+	for temp != nil {
+		fmt.Printf("%d", temp.Val)
+		if temp.Next != nil {
+			fmt.Printf("%s", "->")
+		}
+		temp = temp.Next
+	}
+	fmt.Println()
+}
+
+func rotateRight(head *ListNode, k int) *ListNode {
+	if k == 0 {
+		return head
+	}
+	var length = 0
+	var cursor = head
+	for cursor != nil {
+		cursor = cursor.Next
+		length++
+	}
+
+	if length == 0 || k%length == 0 {
+		return head
+	}
+
+	var pos = length - k%length
+	var newHead *ListNode
+	cursor = head
+	for i := 1; i < pos; i++ {
+		cursor = cursor.Next
+	}
+
+	newHead = cursor.Next
+	cursor.Next = nil
+	cursor = newHead
+	for cursor.Next != nil {
+		cursor = cursor.Next
+	}
+	cursor.Next = head
+	return newHead
+}