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p82

admin 11月 12, 2020 0

LeetCode p82 Remove Duplicates from Sorted List II 题解

1.题目：

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

题意：

输入一个链表，剔除其中所有重复出现过的数字。

2.解题思路:

见代码

3.代码

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 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class  {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode ans = new ListNode(0);
		ans.next = head;
		HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
		while (head != null) {
			map.put(head.val, map.getOrDefault(head.val, 0) + 1);
			head = head.next;
		}
		head = ans;
		while (head != null && head.next != null) {
			if (map.get(head.next.val) > 1) {
				head.next = head.next.next;
				continue;
			}
			head = head.next;
		}
		return ans.next;
    }
}

4.一些总结：