題目描述

輸入兩個單調遞增的連結串列，輸出兩個連結串列合成後的連結串列，當然我們需要合成後的連結串列滿足單調不減規則

題目連結：https://www.nowcoder.com/practice/d8b6b4358f774294a89de2a6ac4d9337

public class Solution {
    public ListNode Merge(ListNode list1, ListNode list2) {
        if (list1 == null) return list2;
        if (list2 == null) return
 
 list1;
        // 遞迴
        ListNode head = null;
        ListNode current = null;
        while (list1 != null && list2 != null) {
            if (list1.val <= list2.val) {
                if (head == null) {
                    head = current = list1;
                } else {
                    current.
 
next = list1;
                    current = current.next;
                }
                list1 = list1.next;
            } else {
                if (head == null) {
                    head = current = list2;
                } else {
                    current.next = list2;
                    current =
 
 current.next;
                }
                list2 = list2.next;
            }
        }
        if (list1 == null) current.next = list2;
        else current.next = list1;
        return head;
    }
}