LRU算法实现（含输入和输出）

Java代码

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Scanner;

// 定义缓存结构体（用到了LinkedHashMap数据结构）
class LRUCache {

    private Map<Integer, Integer> map;
    private int capacity;

    public LRUCache(int capacity) {
        this.capacity = capacity;
        map = new LinkedHashMap<>(capacity);
    }

    public int get(int key) {
        Integer value = map.get(key);
        // 如果已经有此key
        if(value != null){
            if(map.size() > 1){
                // 缓存中值的个数多于一个
                map.remove(key); // 删除原先的key
                map.put(key, value); // 将此key添加到最后
            }
        } else {
            // 如果没有此key
            return -1;
        }
        return value;
    }

    public void put(int key, int value) {
        // 如果已有此key
        if(map.containsKey(key)){
            map.remove(key); // 删除原先的key
        } else if(map.size() >= capacity){
            // 如果此key是新值，且加入此key后，超过了缓存的最大值
            Integer firstKey = map.keySet().iterator().next();
            map.remove(firstKey);
        }
        map.put(key, value);
    }
}
// 输入和输出
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.nextLine();
        String s2 = scanner.nextLine();
        // String s1 = "[\"LRUCache\", \"put\", \"put\", \"get\", \"put\", \"get\", \"put\", \"get\", \"get\", \"get\"]";
        // String s2 = "[[2], [1, 1], [2, 2], [1], [3, 3], [2], [4, 4], [1], [3], [4]]";

        String[] sc1 = s1.substring(1, s1.length() - 1).split(",");
        String[] sc2 = s2.substring(1, s2.length() - 2).split("],");
        StringBuilder result = new StringBuilder();
        LRUCache lruCache = null;
        for (int i = 0; i < sc1.length; i++) {
            if (sc1[i].equals("\"LRUCache\"")){
                lruCache = new LRUCache(Integer.valueOf(sc2[i].substring(1)));
                result.append("null, ");
            } else if (sc1[i].equals(" \"put\"")){
                lruCache.put(Integer.valueOf(sc2[i].substring(2, 3)), Integer.valueOf(sc2[i].substring(5)));
                result.append("null, ");
            } else if (sc1[i].equals(" \"get\"")){
                int val = lruCache.get(Integer.valueOf(sc2[i].substring(2)));
                result.append(val + ", ");
            }
        }
        String res = "[" + result.substring(0, result.length() - 2) + "]";
        System.out.println(res);

    }
}