leetcode — two-sum-ii-input-array-is-sorted

import java.util.ArrayList;
import java.util.List;

/**
* Source : https://oj.leetcode.com/problems/merge-two-sorted-lists/ *
* Created by lverpeng on 2017/7/11.
*
* 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.
*/
public class MergeTwoSortedList {

/**
* 把两个链表合并到一个新的链表中
* 保存新的链表头head，使用一个新链表的指针的current用来指向新链表的尾部，用来添加新的元素
*
* 最后加入较长链表的其余元素
*
* @param list1
* @param list2
* @return
*/
public Node merge (Node list1, Node list2) {
Node head = null;
Node current = null;
while (list1 != null && list2 != null) {
Node n = null;
if (list1.value < list2.value) {
n = list1;
list1 = list1.next;
} else {
n = list2;
list2 = list2.next;
}
if (head == null) {
head = current = n;
} else {
current.next = n;
current = current.next;
}

}
list1 = list1 == null ? list2 : list1;

if (list1 != null) {
if (head != null && current != null) {
current.next = list1;
} else {
head = list1;
}
}

return head;
}

private static class Node {
int value;
Node next;

@Override
public String toString() {
return "Node{" +
"value=" + value +
", next=" + (next == null ? "" : next.value) +
'}';
}
}

private static void print (Node node) {
while (node != null) {
System.out.println(node);
node = node.next;
}
}

public static void main(String[] args) {
MergeTwoSortedList mergeTwoSortedList = new MergeTwoSortedList();
Node list1 = new Node();
Node pointer1 = list1;
list1.value = 1;
Node list2 = new Node();
list2.value = 2;
Node pointer2 = list2;
for (int i = 3; i < 10; i++) {
Node node = new Node();
node.value = i;
if (i % 2 == 1) {
pointer1.next = node;
pointer1 = pointer1.next;
} else {
pointer2.next = node;
pointer2 = pointer2.next;
}
}
print(list1);
System.out.println();
print(list2);
System.out.println();
Node result = mergeTwoSortedList.merge(list1, list2);
print(result);

}
}