add 2074

fishercoder1534 · fishercoder1534 · commit dfa38c964682 · 2021-11-13T21:52:58.000-08:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ &#9733;
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                  
 |-----|----------------|---------------|--------|-------------|-------------
+|2074|[Reverse Nodes in Even Length Groups](https://leetcode.com/problems/reverse-nodes-in-even-length-groups/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2074.java) ||Medium||
 |2073|[Time Needed to Buy Tickets](https://leetcode.com/problems/time-needed-to-buy-tickets/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2073.java) ||Easy||
 |2070|[Most Beautiful Item for Each Query](https://leetcode.com/problems/most-beautiful-item-for-each-query/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2070.java) ||Medium||
 |2068|[Check Whether Two Strings are Almost Equivalent](https://leetcode.com/problems/check-whether-two-strings-are-almost-equivalent/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2068.java) ||Easy||
diff --git a/src/main/java/com/fishercoder/solutions/_2074.java b/src/main/java/com/fishercoder/solutions/_2074.java
@@ -0,0 +1,49 @@
+package com.fishercoder.solutions;
+
+import com.fishercoder.common.classes.ListNode;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class _2074 {
+    public static class Solution1 {
+        public ListNode reverseEvenLengthGroups(ListNode head) {
+            List<Integer> list = new ArrayList<>();
+            ListNode tmp = head;
+            while (tmp != null) {
+                list.add(tmp.val);
+                tmp = tmp.next;
+            }
+            int len = 1;
+            int start = 0;
+            List<Integer> reversed = new ArrayList<>();
+            while (start + len <= list.size()) {
+                if (len % 2 == 0) {
+                    List<Integer> sub = list.subList(start, start + len);
+                    Collections.reverse(sub);
+                    reversed.addAll(sub);
+                } else {
+                    reversed.addAll(list.subList(start, start + len));
+                }
+                start += len;
+                len++;
+            }
+            if (start < list.size()) {
+                List<Integer> sublist = list.subList(start, list.size());
+                if (sublist.size() % 2 == 0) {
+                    Collections.reverse(sublist);
+                }
+                reversed.addAll(sublist);
+            }
+            ListNode pre = new ListNode(-1);
+            head = new ListNode(reversed.get(0));
+            pre.next = head;
+            for (int i = 1; i < reversed.size(); i++) {
+                head.next = new ListNode(reversed.get(i));
+                head = head.next;
+            }
+            return pre.next;
+        }
+    }
+}
