1分钟 - Linked List Cycle II
来源:互联网 发布:sql字符串截断怎么改 编辑:程序博客网 时间:2024/05/16 09:45
Given a linked list, return the node where the cycle begins. If there is no cycle, return null
.
Follow up:
Can you solve it without using extra space?
/**
* Definition for singly-linked list.
* class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public ListNode detectCycle(ListNode head) {
HashSet<ListNode> nodes = new HashSet<ListNode>();
ListNode current = head;
while (current != null) {
if (nodes.contains(current)) {
return current;
} else {
nodes.add(current);
}
current = current.next;
}
return null;
}
}
Follow up :
已经知道怎么做了就么意思了。随便写写3分钟写出来算了。
/**
* Definition for singly-linked list.
* class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public ListNode detectCycle(ListNode head) {
HashSet<ListNode> nodes = new HashSet<ListNode>();
ListNode slow = head;
ListNode fast = head;
while (fast != null) {
fast = fast.next;
if (fast == null) {
return null;
}
fast = fast.next;
slow = slow.next;
if (slow == fast) {
break;
}
}
if (fast == null) {
return null;
}
fast = head;
while (fast != slow) {
slow = slow.next;
fast = fast.next;
}
return fast;
}
}
- 1分钟 - Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- Linked List Cycle II
- MFC 消息映射机制剖析
- NO_36_Double-base palindromes
- 愤慨的小鸟-----小鸟群筹办动画
- 类的自动类型转换和强制类型转换
- cocos2dx3.0无法取消Armatrue骨骼动画中的补间效果问题的解决办法
- 1分钟 - Linked List Cycle II
- 大数问题 ZOJ Problem Set - 2001 Adding Reversed Numbers
- 呼叫覆盖(Call Coverage)功能汇总
- Objective-c语法之基本数据类型转换&使用
- 1442 Black Box
- POJ1511Invitation Cards(国产算法SPFA)
- Android实践--如何提高Android模拟器的运行速度
- android 欢迎界面的实现在一个activity中
- ReadData