Commit 9f81c74

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增加代码

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	`1`	`+/*`
	`2`	`+ * @lc app=leetcode.cn id=141 lang=java`
	`3`	`+ *`
	`4`	`+ * [141] 环形链表`
	`5`	`+ */`
	`6`	`+`
	`7`	`+// @lc code=start`
	`8`	`+/**`
	`9`	`+ * Definition for singly-linked list.`
	`10`	`+ * class ListNode {`
	`11`	`+ * int val;`
	`12`	`+ * ListNode next;`
	`13`	`+ * ListNode(int x) {`
	`14`	`+ * val = x;`
	`15`	`+ * next = null;`
	`16`	`+ * }`
	`17`	`+ * }`
	`18`	`+ */`
	`19`	`+public class Solution {`
	`20`	`+ public boolean hasCycle(ListNode head) {`
	`21`	`+ if(head == null) return false;`
	`22`	`+ ListNode slow = head;`
	`23`	`+ ListNode fast = head.next;`
	`24`	`+`
	`25`	`+ while(fast != null && fast.next != null) {`
	`26`	`+ if(slow == fast) {`
	`27`	`+ return true;`
	`28`	`+ }`
	`29`	`+`
	`30`	`+ slow = slow.next;`
	`31`	`+ fast = fast.next.next;`
	`32`	`+ }`
	`33`	`+`
	`34`	`+ return false;`
	`35`	`+ }`
	`36`	`+}`
	`37`	`+// @lc code=end`
	`38`	`+`

Lines changed: 44 additions & 0 deletions

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	`1`	`+/*`
	`2`	`+ * @lc app=leetcode.cn id=142 lang=java`
	`3`	`+ *`
	`4`	`+ * [142] 环形链表 II`
	`5`	`+ */`
	`6`	`+`
	`7`	`+// @lc code=start`
	`8`	`+/**`
	`9`	`+ * Definition for singly-linked list.`
	`10`	`+ * class ListNode {`
	`11`	`+ * int val;`
	`12`	`+ * ListNode next;`
	`13`	`+ * ListNode(int x) {`
	`14`	`+ * val = x;`
	`15`	`+ * next = null;`
	`16`	`+ * }`
	`17`	`+ * }`
	`18`	`+ */`
	`19`	`+public class Solution {`
	`20`	`+ public ListNode detectCycle(ListNode head) {`
	`21`	`+ if(head == null) return null;`
	`22`	`+`
	`23`	`+ ListNode slow = head;`
	`24`	`+ ListNode fast = head;`
	`25`	`+`
	`26`	`+ while(fast != null && fast.next != null) {`
	`27`	`+ fast = fast.next.next;`
	`28`	`+ slow = slow.next;`
	`29`	`+ if(slow == fast) {`
	`30`	`+ fast = head;`
	`31`	`+ while(fast != slow) {`
	`32`	`+ fast = fast.next;`
	`33`	`+ slow = slow.next;`
	`34`	`+ }`
	`35`	`+`
	`36`	`+ return slow;`
	`37`	`+ }`
	`38`	`+ }`
	`39`	`+`
	`40`	`+ return null;`
	`41`	`+ }`
	`42`	`+}`
	`43`	`+// @lc code=end`
	`44`	`+`

Lines changed: 63 additions & 0 deletions

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	`1`	`+/*`
	`2`	`+ * @lc app=leetcode.cn id=234 lang=java`
	`3`	`+ *`
	`4`	`+ * [234] 回文链表`
	`5`	`+ */`
	`6`	`+`
	`7`	`+// @lc code=start`
	`8`	`+/**`
	`9`	`+ * Definition for singly-linked list.`
	`10`	`+ * public class ListNode {`
	`11`	`+ * int val;`
	`12`	`+ * ListNode next;`
	`13`	`+ * ListNode() {}`
	`14`	`+ * ListNode(int val) { this.val = val; }`
	`15`	`+ * ListNode(int val, ListNode next) { this.val = val; this.next = next; }`
	`16`	`+ * }`
	`17`	`+ */`
	`18`	`+class Solution {`
	`19`	`+ public boolean isPalindrome(ListNode head) {`
	`20`	`+ if(head == null) return true;`
	`21`	`+`
	`22`	`+ ListNode slow = head;`
	`23`	`+ ListNode fast = head.next;`
	`24`	`+`
	`25`	`+ while(fast != null && fast.next != null) {`
	`26`	`+ slow = slow.next;`
	`27`	`+ fast = fast.next.next;`
	`28`	`+ }`
	`29`	`+`
	`30`	`+ ListNode tail = reverse(slow.next);`
	`31`	`+ slow.next = null;`
	`32`	`+`
	`33`	`+ while(head != null && tail != null) {`
	`34`	`+ if(head.val != tail.val) {`
	`35`	`+ return false;`
	`36`	`+ }`
	`37`	`+`
	`38`	`+ head = head.next;`
	`39`	`+ tail = tail.next;`
	`40`	`+ }`
	`41`	`+`
	`42`	`+ return true;`
	`43`	`+`
	`44`	`+ }`
	`45`	`+`
	`46`	`+ private ListNode reverse(ListNode node) {`
	`47`	`+ if(node == null) return null;`
	`48`	`+`
	`49`	`+ ListNode dummy = new ListNode();`
	`50`	`+ while(node != null) {`
	`51`	`+ ListNode tmp = node.next;`
	`52`	`+ node.next = dummy.next;`
	`53`	`+ dummy.next = node;`
	`54`	`+ node = tmp;`
	`55`	`+ }`
	`56`	`+`
	`57`	`+ return dummy.next;`
	`58`	`+ }`
	`59`	`+`
	`60`	`+`
	`61`	`+}`
	`62`	`+// @lc code=end`
	`63`	`+`

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