相交链表
点击查看代码
/*** Definition for singly-linked list.* public class ListNode {* int val;* ListNode next;* ListNode(int x) {* val = x;* next = null;* }* }*/
public class Solution {public ListNode getIntersectionNode(ListNode headA, ListNode headB) {ListNode A = headA;int a = 0;while(A != null){A = A.next;a += 1;}ListNode B = headB;int b = 0;while(B != null){B = B.next;b += 1;}if(a > b){int c = a - b;while(c != 0){headA = headA.next;c--;}}else{int c = b - a;while(c != 0){headB = headB.next;c--;}}while(headA != headB){headA = headA.next;headB = headB.next;}return headA;}
}
234.回文链表
快慢指针找中点。
class Solution {
public boolean isPalindrome(ListNode head) {
ListNode fast = head;
ListNode slow = head;
while(fast != null && fast.next != null){
fast = fast.next.next;
slow = slow.next;
}
ListNode pre = null;
ListNode cur = slow;
while(cur != null){
ListNode next = cur.next;
cur.next = pre;
pre = cur;
cur = next;
}
while(pre != null){
if(pre.val != head.val) return false;
pre = pre.next;
head = head.next;
}
return true;
}
}
141环形链表
快慢指针
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public class Solution {public boolean hasCycle(ListNode head) {ListNode slow = head;ListNode fast = head;while(fast != null && fast.next != null){fast = fast.next.next;slow = slow.next;if(fast == slow){return true;}}return false;}
}