題目描述
輸入兩個(gè)單調(diào)遞增的鏈表，輸出兩個(gè)鏈表合成后的鏈表，當(dāng)然我們需要合成后的鏈表滿足單調(diào)不減規(guī)則。

public class Solution {
    
    public ListNode Merge(ListNode list1,ListNode list2) {
    
        ListNode pre1, post1;
        pre1 = post1 = list1;
        ListNode pre = list2;
        while(post1 != null && pre != null) {
            
            if(post1.val <= pre.val) {
                
                pre1 = post1;
                post1 = post1.next;
            }else {
                
                if(post1 == pre1) {
                    
                    ListNode temp = pre;
                    pre = pre.next;
                    temp.next = post1;
                    pre1 = temp;
                }else {
                    
                    ListNode temp = pre;
                    pre = pre.next;
                    temp.next =post1;
                    pre1.next = temp;
                    
                }
            }
            
        }
        while(pre != null) {
            
            pre1.next =pre;
            pre = pre.next;
        }
        return list1;
    }
    public static void main(String[] args) {
        
        ListNode list1 = new ListNode(0);
        ListNode list2 = new ListNode(0);
        ListNode node = list1;
        for(int i = 1; i <= 5; i+=2){
            
            ListNode temp = new ListNode(i);
            node.next = temp;
            node = node.next;
        }
        node = list2;
        for(int i = 2; i <= 6; i+=2) {
            
            ListNode temp = new ListNode(i);
            node.next = temp;
            node = node.next;
        }
        Solution obj = new Solution();
        node = obj.Merge(list1, list2);
        for(ListNode i = node; i != null; i = i.next){
            
            System.out.println(i.val);
        }
    }
}