Remove Duplicates From an Unsorted Linked List

给一个链表, 删除里面所有重复的元素, 链表本身不是已排序的.

因为没有排序, 所以要用set查重. 然后新建个链表返回即可.

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {

    public ListNode deleteDuplicatesUnsorted(ListNode head) {
        Map<Integer, Integer> count = new HashMap<>();
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        while(dummy.next != null) {
            count.put(dummy.next.val, count.getOrDefault(dummy.next.val, 0) + 1);
            dummy = dummy.next;
        }
        ListNode dn = new ListNode(0); 
        ListNode res = dn;
        while(head != null) {
            if(count.get(head.val) <= 1){
                dn.next = new ListNode(head.val);
                dn = dn.next;
            }
            head = head.next;
        }
        return res.next;
    }
}

/**

* Definition for singly-linked list.

* public class ListNode {

* int val;

* ListNode next;

* ListNode() {}

* ListNode(int val) { this.val = val; }

* ListNode(int val, ListNode next) { this.val = val; this.next = next; }

* }

class Solution {

public ListNode deleteDuplicatesUnsorted(ListNode head) {

Map<Integer, Integer> count = new HashMap<>();

ListNode dummy = new ListNode(0);

dummy.next = head;

while(dummy.next != null) {

count.put(dummy.next.val, count.getOrDefault(dummy.next.val, 0) + 1);

dummy = dummy.next;

}

ListNode dn = new ListNode(0);

ListNode res = dn;

while(head != null) {

if(count.get(head.val) <= 1){

dn.next = new ListNode(head.val);

dn = dn.next;

}

head = head.next;

}

return res.next;

}

Remove Duplicates From an Unsorted Linked List

书脊

这青苔碧瓦堆, 俺曾睡风流觉, 将五十年兴亡看饱.

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