1882. Process Tasks Using Servers

class Solution:
    def assignTasks(self, servers: List[int], tasks: List[int]) -> List[int]:
        """ tc O(SlgS+T*lgT)  sc O(S)
        main idea: two PQ    
        """
        
        
        available = [[w,j] for j,w in enumerate(servers)] # (weight,idex)
        unava = [] # (available at time ,w, idx)
        heapq.heapify(available)
        cur_t = 0 
        n = len(tasks)
        res = []#[-1] *n
        for i in range(n):
            cur_t = max(i,cur_t)  # current time can be larger than i because there may be no available server at cur_t 
             
            if len(available) == 0:  # need to wait until earliest available time in  unavailable  queue
                cur_t = unava[0][0]
                
            while unava and cur_t >= unava[0][0]:
                tt,w,idx = heappop(unava)
                heappush(available,[w,idx])
                
            w,idx = heappop(available)
            new_available_time = cur_t + tasks[i]
            res.append(idx)
            heappush(unava,[new_available_time,w,idx])
        return res