[leetcode] Merge Two Sorted Lists

Merge Two Sorted Lists

Total Accepted: 41990 Total
Submissions: 126215My Submissions

Question
Solution

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

package com.wyt.leetcodeOJ;

public class MergeTwoSortedLists {

public static void main(String[] args) {
ListNode node11 = new ListNode(-10);
ListNode node12 = new ListNode(-9);
ListNode node13 = new ListNode(-6);
ListNode node14 = new ListNode(1);
ListNode node15 = new ListNode(9);
ListNode node16 = new ListNode(9);
//		ListNode node17 = new ListNode(6);
node11.next = node12;
node12.next = node13;
node13.next = node14;
node14.next = node15;
node15.next = node16;
//		node16.next = node17;

ListNode node21 = new ListNode(-5);
ListNode node22 = new ListNode(-3);
ListNode node23 = new ListNode(0);
ListNode node24 = new ListNode(7);
ListNode node25 = new ListNode(8);
ListNode node26 = new ListNode(8);
node21.next = node22;
node22.next = node23;
node23.next = node24;
node24.next = node25;
node25.next = node26;

ListNode reListNode = mergeTwoLists(node11, node21);

System.out.println(reListNode);

}

public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {

if (l1 == null) {
return l2;
}
if (l2 == null) {
return l1;
}
ListNode p, q, result;
if(l1.val < l2.val) {
result = l1;
p = l1;
q = l2;
} else {
result = l2;
p = l2;
q = l1;
}

while(p.next != null) {
if (q == null) {
break;
}
ListNode tmp = new ListNode(q.val);
if(p.next.val > tmp.val) {//p点的值大于q，将q插到p后面，p,q后移
tmp.next = p.next;
p.next = tmp;
p = p.next;
//p = p.next.next;
q = q.next;
} else {//p点小于等于q,插到后面的后面
if (p.next.next != null) {
if(p.next.next.val > tmp.val) {
tmp.next = p.next.next;
p.next.next = tmp;
p = p.next;
q = q.next;
} else {
p = p.next.next;
}
} else {
p.next.next = q;
q = null;
break;
}
}
}

if(q != null) {
p.next = q;
}

return result;
}

public static ListNode mergeTwoListsRecursive(ListNode l1, ListNode l2) {
if(l2==null) return l1;
if(l1==null) return l2;

if(l1.val<=l2.val){
l1.next = mergeTwoListsRecursive(l1.next,l2);
return l1;
}
else{
l2.next = mergeTwoListsRecursive(l1,l2.next);
return l2;
}
}

}