题解 | #牛牛的门票缓存系统#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param operations string字符串一维数组 
     * @param data int整型二维数组 
     * @param capacity int整型 
     * @return int整型一维数组
     */
    public int[] performOperation (String[] operations, int[][] data, int capacity) {
        // write code here
        TicketCache ticketCache = new TicketCache(capacity);
        List<Integer> returnL = new ArrayList<>();
        for (int i=0; i < operations.length; i++){
            if (operations[i].equals("putTicket")){
                ticketCache.putTicket(data[i][0], data[i][1]);
            }else if (operations[i].equals("getTicket")){
                int info = ticketCache.getTicket(data[i][0]);
                returnL.add(info);
            }
        }
        int[] returnA = returnL.stream().mapToInt(Integer::valueOf).toArray();
        return returnA;
    }

    public class TicketCache{
        int capacity;
        Map<Integer, Integer> tickectInfoMap;
        LinkedList<Integer> linkedL;
       
        public TicketCache(int capacity){
            this.capacity = capacity;
            this.tickectInfoMap = new HashMap<>();
            this.linkedL = new LinkedList<>();
        }

        public int getTicket(int ticketId){
            if (tickectInfoMap.containsKey(Integer.valueOf(ticketId))){
                int info = tickectInfoMap.get(Integer.valueOf(ticketId));
                linkedL.removeFirstOccurrence(ticketId);
                linkedL.addLast(ticketId);
                return info;
            }
            return -1;
        }

        public void putTicket(int ticketId, int ticketInfo){
            if (this.capacity <= 0){
                return;
            }
            if (tickectInfoMap.size() >= this.capacity){
                Integer toRemove = linkedL.getFirst();
                tickectInfoMap.remove(toRemove);
                linkedL.removeFirst();
            }
            tickectInfoMap.put(Integer.valueOf(ticketId), Integer.valueOf(ticketInfo));
            linkedL.addFirst(ticketId);
        }
    }
}