# 1171. Remove Zero Sum Consecutive Nodes from Linked List
###### tags: `Leetcode` `Medium` `Linked List` `Prefix Sum`
Link: https://leetcode.com/problems/remove-zero-sum-consecutive-nodes-from-linked-list/description/
## 思路
首先思考 如果不是linkedlist 是一个array 我们求prefixSum 然后存在map中 如果出现了重复的prefix 说明中间这段可以被删掉
linked list也是一样的做法
但需要注意的是如果我们把一段node删掉就需要把这一段node所有prefix从map里面删掉 (line 13-19)
## Code

class Solution {
    public ListNode removeZeroSumSublists(ListNode head) {
        Map<Integer, ListNode> map = new HashMap<>();
        ListNode dummyNode = new ListNode(0, head);
        map.put(0, dummyNode);
        ListNode curr = head;
        int sum = 0;
        while(curr!=null){
            sum += curr.val;
            ListNode next = curr.next;
            if(map.containsKey(sum)){
                ListNode prev = map.get(sum);
                ListNode tempcur = prev.next;
                int p = sum+tempcur.val;
                while(p!=sum){
                    map.remove(p);
                    tempcur = tempcur.next;
                    p += tempcur.val;
                }
                prev.next = next;
            }
            else map.put(sum, curr);
            curr = next;
        }
        return dummyNode.next;
    }
}