1171. Remove Zero Sum Consecutive Nodes from Linked List

class Solution {
public:
    ListNode* removeZeroSumSublists(ListNode* head) {
        ListNode node=ListNode(0, head);
        ListNode* ptr=&node;
        int prefix=1000000;// The min value for prefix>=-1e6
        static ListNode* mp[2000001]={NULL};
        for( ; ptr; ptr=ptr->next){
            prefix+=(ptr->val);
            mp[prefix]=ptr;
        }
        prefix=1000000, ptr=&node;//reset
        for( ;ptr; ptr=ptr->next){
            prefix+=(ptr->val);
            ptr->next=mp[prefix]->next;
        }
        return node.next;
    }
};