Fix 0019

leetcode/0019.Remove-Nth-Node-From-End-of-List/19. Remove Nth Node From End of List.go

@@ -20,8 +20,14 @@ func removeNthFromEnd(head *ListNode, n int) *ListNode {
 	var fast, slow *ListNode
 	fast = head
 	slow = head
+	step := 0
 	for i := 0; i < n; i++ {
+		// n maybe much larger than length of linklist
+		if fast.Next == nil && step != 0 && step < n-1 {
+			return head
+		}
 		fast = fast.Next
+		step++
 	}
 	if fast == nil {
 		head = head.Next

leetcode/0019.Remove-Nth-Node-From-End-of-List/19. Remove Nth Node From End of List_test.go

@@ -29,6 +29,21 @@ func Test_Problem19(t *testing.T) {
 
 	qs := []question19{
 
+		{
+			para19{[]int{1, 2}, 2},
+			ans19{[]int{2}},
+		},
+
+		{
+			para19{[]int{1}, 1},
+			ans19{[]int{}},
+		},
+
+		{
+			para19{[]int{1, 2, 3, 4, 5}, 10},
+			ans19{[]int{1, 2, 3, 4, 5}},
+		},
+
 		{
 			para19{[]int{1, 2, 3, 4, 5}, 1},
 			ans19{[]int{1, 2, 3, 4}},