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java 实现单链表逆转详解及实例代码

2017-02-28 09:07 951 查看

java 实现单链表逆转详解

实例代码:

class Node {
Node next;
String name;
public Node(String name) {
this.name = name;
}
/**
* 打印结点
*/
public void show() {
Node temp = this;
do {
System.out.print(temp + "->");
temp = temp.next;
}while(temp != null);
System.out.println();
}
/**
* 递归实现单链表反转,注意:单链表过长,会出现StackOverflowError
* @param n
* @return
*/
public static Node recursionReverse(Node n) {
long start = System.currentTimeMillis();
if(n == null || n.next == null) {
return n;
}
Node reverseNode = recursionReverse(n.next);
n.next.next = n;
n.next = null;
System.out.println("递归逆置耗时:" + (System.currentTimeMillis() - start) + "ms...");
return reverseNode;
}
/**
* 循环实现单链表反转
* @param n
* @return
*/
public static Node loopReverse(Node n) {
long start = System.currentTimeMillis();
if(n == null || n.next == null) {
return n;
}
Node pre = n;
Node cur = n.next;
Node next = null;
while(cur != null) {
next = cur.next;
cur.next = pre;
pre = cur;
cur = next;
}
n.next = null;
n = pre;
System.out.println("循环逆置耗时:" + (System.currentTimeMillis() - start) + "ms...");
return pre;
}
@Override
public String toString() {
return name;
}
  
  public static void main(String[] args) {
int len = 10;
Node[] nodes = new Node[len];
for(int i = 0; i < len; i++) {
nodes[i] = new Node(i + "");
}
for(int i = 0; i < len - 1; i++) {
nodes[i].next = nodes[i+1];
}
/* try {
Thread.sleep(120000);
} catch (InterruptedException e) {
e.printStackTrace();
}*/
Node r1 = Node.loopReverse(nodes[0]);
r1.show();
Node r = Node.recursionReverse(r1);
r.show();
} 
}

总结

对于递归和循环,推荐使用循环实现,递归在单链表过大时,会出现StatckOverflowError,递归涉及到方法的调用,在性能上也弱于循环的实现

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标签:  java 单链表 逆转