feat: 2025-10-27打卡

61.rotate-list.java

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+/*
+ * @lc app=leetcode id=61 lang=java
+ *
+ * [61] Rotate List
+ */
+
+// @lc code=start
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+    public ListNode rotateRight(ListNode head, int k) {
+        if(head == null) {
+            return head;
+        }
+        int len = 0;
+        ListNode cur = head;
+        while(cur != null) {
+            len++;
+            if(cur.next == null) {
+                cur.next = head;
+                break;
+            }
+            cur = cur.next;
+        }
+        k = k % len;
+        ListNode prev = cur;
+        cur = head;
+        for(int i = 0; i < len - k; i++) {
+            cur = cur.next;
+            prev = prev.next;
+        }
+        prev.next = null;
+        return cur;
+    }
+}
+// @lc code=end
+