递归和非递归方式合并有序链表

给定两个有序单链表，合并成一个新的有序链表，分别用递归和非递归的方式实现如下：

package algorithm;

public class MergeSortLinkList {

public static void main(String[] args) {
Node[] nodes = createData();
// Node node = mergeByRecursion(nodes[0], nodes[1]);
Node node = merge(nodes[0], nodes[1]);
print(node);
}

public static Node[] createData() {
Node node1 = new Node(0, null);
Node head1 = node1;
Node node2 = new Node(0, null);
Node head2 = node2;
for (int i = 1; i <= 10; i++) {
Node tmp1 = new Node(i, null);
node1.next = tmp1;
node1 = tmp1;
}
for (int i = 1; i <= 1000; i++) {
Node tmp2 = new Node(i, null);
node2.next = tmp2;
node2 = tmp2;
}
Node[] nodes = new Node[2];
nodes[0] = head1;
nodes[1] = head2;
return nodes;
}

public static Node mergeByRecursion(Node node1, Node node2) {
if (node1 == null) {
return node2;
} else if (node2 == null) {
return node1;
}
if (node1.value < node2.value) {
node1.next = merge(node1.next, node2);
return node1;
} else {
node2.next = merge(node2.next, node1);
return node2;
}
}

public static Node merge(Node node1, Node node2) {
if (node1 == null) {
return node2;
} else if (node2 == null) {
return node1;
}
//先得到头部指针
Node node = null;
if (node1.value < node2.value) {
node = node1;
node1 = node1.next;
} else {
node = node2;
node2 = node2.next;
}
//保存头部指针
Node head = node;
//循环移动节点
while (node1 != null && node2 != null) {
if (node1.value < node2.value) {
node.next = node1;
node = node1;
node1 = node1.next;
} else {
node.next = node2;
node = node2;
node2 = node2.next;
}
}
//当两个链表长度不一致时的处理
if (node1 == null) {
node.next = node2;
} else {
node.next = node1;
}
return head;
}

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

}

class Node {
public int value;
public Node next;

public Node(int value, Node next) {
this.value = value;
this.next = next;
}
}


递归方法实现更加优雅，但缺陷在于限制了链表长度，否则会存在栈溢出的问题。