bool operator () (ListNode *x, ListNode *y) {

return x->val > y->val;

}

ListNode *mergeKLists(vector<ListNode *> &lists) {

// Start typing your C/C++ solution below

// DO NOT write int main() function

ListNode *ret = NULL;

ListNode **pCur = &ret;

ListNode *tmp = NULL;

if (lists.size() == 0) {

return ret;

}

priority_queue<ListNode *, vector<ListNode *>, cmp> que;

for (int i = 0; i < lists.size(); i++) {

if (lists[i] != NULL) {

que.push(lists[i]);

}

}

while (!que.empty()) {

tmp = que.top();

que.pop();

*pCur = tmp;

pCur = &((*pCur)->next);

if (tmp->next != NULL) {

que.push(tmp->next);

}

}

return ret;

}