LC.P1171[从链表中删去总和值为零的连续节点]

方法一：前缀和+哈希表

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/**
 * 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 removeZeroSumSublists(ListNode head) {
        ListNode dummy = new ListNode(0, head);
        Map<Integer, ListNode> map = new HashMap<>();
        int sum = 0;
        ListNode p = dummy;
        while (p != null) {
            sum += p.val;
            map.put(sum, p);
            p = p.next;
        }
        sum = 0;
        p = dummy;
        while (p != null) {
            sum += p.val;
            p.next = map.get(sum).next;
            p = p.next;
        }
        return dummy.next;
    }
}
  • 时间复杂度：$O(n)$
  • 空间复杂度：$O(n)$