Add: Remove Nth Node From End of List

internal/leetcode/problems_status.go

@@ -19,6 +19,7 @@ var problemStatus = map[int]bool{
 	16:   true,
 	17:   true,
 	18:   true,
+	19:   true,
 	20:   true,
 	21:   true,
 	22:   true,

problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list.go

@@ -1 +1,28 @@
 package problem19
+
+import "github.com/openset/leetcode/internal/kit"
+
+// ListNode - Definition for singly-linked list.
+type ListNode = kit.ListNode
+
+/**
+ * Definition for singly-linked list.
+ * type ListNode struct {
+ *     Val int
+ *     Next *ListNode
+ * }
+ */
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+	ans := &ListNode{Next: head}
+	pos := ans
+	for head != nil {
+		head = head.Next
+		if n > 0 {
+			n--
+		} else {
+			pos = pos.Next
+		}
+	}
+	pos.Next = pos.Next.Next
+	return ans.Next
+}

problems/remove-nth-node-from-end-of-list/remove_nth_node_from_end_of_list_test.go

@@ -1 +1,40 @@
 package problem19
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/openset/leetcode/internal/kit"
+)
+
+type testType struct {
+	in   []int
+	n    int
+	want []int
+}
+
+func TestRemoveNthFromEnd(t *testing.T) {
+	tests := [...]testType{
+		{
+			in:   []int{1, 2, 3, 4, 5},
+			n:    2,
+			want: []int{1, 2, 3, 5},
+		},
+		{
+			in:   []int{1, 2, 3, 4, 5},
+			n:    5,
+			want: []int{2, 3, 4, 5},
+		},
+		{
+			in:   []int{1, 2, 3, 4, 5},
+			n:    1,
+			want: []int{1, 2, 3, 4},
+		},
+	}
+	for _, tt := range tests {
+		got := removeNthFromEnd(kit.SliceInt2ListNode(tt.in), tt.n)
+		if !reflect.DeepEqual(kit.ListNode2SliceInt(got), tt.want) {
+			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
+		}
+	}
+}