23:合并K个升序链表

LeetCode/src/main/java/leetcode/editor/cn/MergeKSortedLists.java

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+//给你一个链表数组，每个链表都已经按升序排列。 
+//
+// 请你将所有链表合并到一个升序链表中，返回合并后的链表。 
+//
+// 
+//
+// 示例 1： 
+//
+// 输入：lists = [[1,4,5],[1,3,4],[2,6]]
+//输出：[1,1,2,3,4,4,5,6]
+//解释：链表数组如下：
+//[
+//  1->4->5,
+//  1->3->4,
+//  2->6
+//]
+//将它们合并到一个有序链表中得到。
+//1->1->2->3->4->4->5->6
+// 
+//
+// 示例 2： 
+//
+// 输入：lists = []
+//输出：[]
+// 
+//
+// 示例 3： 
+//
+// 输入：lists = [[]]
+//输出：[]
+// 
+//
+// 
+//
+// 提示： 
+//
+// 
+// k == lists.length 
+// 0 <= k <= 10^4 
+// 0 <= lists[i].length <= 500 
+// -10^4 <= lists[i][j] <= 10^4 
+// lists[i] 按 升序 排列 
+// lists[i].length 的总和不超过 10^4 
+// 
+// Related Topics 堆 链表 分治算法 
+// 👍 1215 👎 0
+
+package leetcode.editor.cn;
+
+import com.code.leet.entiy.ListNode;
+
+//23:合并K个升序链表
+public class MergeKSortedLists{
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new MergeKSortedLists().new Solution();
+    }
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+/**
+ * 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 mergeKLists(ListNode[] lists) {
+        ListNode result = null;
+        for (int i = 0; i < lists.length; i++) {
+            result = mergeTwoLists(result,lists[i]);
+        }
+        return result;
+    }
+    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
+        if (l1 == null) {
+            return l2;
+        }
+        if (l2 == null) {
+            return l1;
+        }
+        if (l1.val < l2.val) {
+            l1.next = mergeTwoLists(l1.next, l2);
+            return l1;
+        } else {
+            l2.next = mergeTwoLists(l1, l2.next);
+            return l2;
+        }
+    }
+}
+//leetcode submit region end(Prohibit modification and deletion)
+
+}