refactor 1721

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_1721.java

@@ -30,37 +30,38 @@ public ListNode swapNodes(ListNode head, int k) {
             return tmp.next;
         }
     }
+
     public static class Solution2 {
         public ListNode swapNodes(ListNode head, int k) {
-            if(head == null || head.next == null){
+            if (head == null || head.next == null) {
                 return head;
             }
 
             // find length of list
             int n = 0;
             ListNode current = head;
-            while(current != null){
+            while (current != null) {
                 current = current.next;
                 n++;
             }
 
             int nums[] = new int[n];
             current = head;
             int i = 0;
-            while(current != null){
+            while (current != null) {
                 nums[i++] = current.val;
                 current = current.next;
             }
-            int firstIndex = 0;
-            int secondIndex = 0;
+            int firstIndex;
+            int secondIndex;
             firstIndex = k;
-            secondIndex = n-k;
-            int temp = nums[firstIndex-1];
-            nums[firstIndex-1] = nums[secondIndex];
+            secondIndex = n - k;
+            int temp = nums[firstIndex - 1];
+            nums[firstIndex - 1] = nums[secondIndex];
             nums[secondIndex] = temp;
             ListNode dummy = new ListNode(-1);
             current = dummy;
-            for(i = 0; i<n; i++){
+            for (i = 0; i < n; i++) {
                 ListNode node = new ListNode(nums[i]);
                 current.next = node;
                 current = current.next;

src/test/java/com/fishercoder/_1721Test.java

@@ -1,37 +1,38 @@
 package com.fishercoder;
 
 import com.fishercoder.common.classes.ListNode;
+import com.fishercoder.common.utils.LinkedListUtils;
 import com.fishercoder.solutions._1721;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
 import static org.junit.Assert.assertEquals;
 
 public class _1721Test {
+    private static _1721.Solution1 solution1;
     private static _1721.Solution2 solution2;
     private static ListNode expected;
     private static ListNode node;
     private static int k;
 
     @BeforeClass
     public static void setup() {
+        solution1 = new _1721.Solution1();
         solution2 = new _1721.Solution2();
     }
 
     @Test
     public void test1() {
-        node = new ListNode(1);
-        node.next = new ListNode(2);
-        node.next.next = new ListNode(3);
-        node.next.next.next = new ListNode(4);
-        node.next.next.next.next = new ListNode(5);
-
-        expected = new ListNode(1);
-        expected.next = new ListNode(4);
-        expected.next.next = new ListNode(3);
-        expected.next.next.next = new ListNode(2);
-        expected.next.next.next.next = new ListNode(5);
+        node = LinkedListUtils.contructLinkedList(new int[]{1, 2, 3, 4, 5});
+        expected = LinkedListUtils.contructLinkedList(new int[]{1, 4, 3, 2, 5});
+        k = 2;
+        assertEquals(expected, solution1.swapNodes(node, k));
+    }
 
+    @Test
+    public void test2() {
+        node = LinkedListUtils.contructLinkedList(new int[]{1, 2, 3, 4, 5});
+        expected = LinkedListUtils.contructLinkedList(new int[]{1, 4, 3, 2, 5});
         k = 2;
         assertEquals(expected, solution2.swapNodes(node, k));
     }