add

5.leetcode/src/com/fanxb/common/Q148.java

@@ -0,0 +1,67 @@
+package com.fanxb.common;
+
+/**
+ * TODO
+ *
+ * @author fanxb
+ * @date 2022/3/7 10:48
+ */
+public class Q148 {
+
+    public static class ListNode {
+        int val;
+        ListNode next;
+
+        ListNode() {
+        }
+
+        ListNode(int val) {
+            this.val = val;
+        }
+
+        ListNode(int val, ListNode next) {
+            this.val = val;
+            this.next = next;
+        }
+    }
+
+    public ListNode sortList(ListNode head) {
+        if (head == null || head.next == null) {
+            return head;
+        }
+        ListNode slow = head;
+        ListNode fast = head;
+        while (fast.next != null && fast.next.next != null) {
+            slow = slow.next;
+            fast = fast.next.next;
+        }
+        //中间节点的下一个节点
+        ListNode slowNext = slow.next;
+        //从中间断开链表
+        slow.next = null;
+        ListNode left = sortList(head);
+        ListNode right = sortList(slowNext);
+        //左右节点进行二路归并
+        ListNode res = new ListNode(), tempRes = res;
+        while (left != null && right != null) {
+            if (left.val < right.val) {
+                tempRes.next = left;
+                left = left.next;
+            } else {
+                tempRes.next = right;
+                right = right.next;
+            }
+            tempRes = tempRes.next;
+        }
+        tempRes.next = left == null ? right : left;
+        return res.next;
+    }
+
+    public static void main(String[] args) {
+        ListNode a1 = new ListNode(4);
+        a1.next = new ListNode(2);
+        a1.next.next = new ListNode(1);
+        a1.next.next.next = new ListNode(3);
+        System.out.println(new Q148().sortList(a1));
+    }
+}