2026年高新科技公司工程师面试题及答案

2026年高新科技公司工程师面试题及答案一、编程语言与数据结构（20分，共4题）题目1（5分）：请用Python实现一个函数，输入一个字符串，返回该字符串中出现频率最高的字符及其出现次数。如果多个字符出现次数相同，返回所有这些字符。pythondeffind_top_frequent_chars(s):fromcollectionsimportCountercounter=Counter(s)max_freq=max(counter.values())return[(char,freq)forchar,freqincounter.items()iffreq==max_freq]示例print(find_top_frequent_chars("helloworld"))题目2（5分）：请解释什么是二叉搜索树(BST)，并实现一个BST的插入操作。pythonclassTreeNode:def__init__(self,val=0,left=None,right=None):self.val=valself.left=leftself.right=rightclassBST:def__init__(self):self.root=Nonedefinsert(self,val):ifself.rootisNone:self.root=TreeNode(val)else:self._insert(self.root,val)def_insert(self,node,val):ifval<node.val:ifnode.leftisNone:node.left=TreeNode(val)else:self._insert(node.left,val)else:ifnode.rightisNone:node.right=TreeNode(val)else:self._insert(node.right,val)示例bst=BST()bst.insert(5)bst.insert(3)bst.insert(7)bst.insert(2)bst.insert(4)bst.insert(6)bst.insert(8)题目3（5分）：请解释什么是动态规划，并给出一个动态规划的经典问题及其解法。python斐波那契数列问题deffibonacci(n):ifn<=1:returnndp=[0](n+1)dp[1]=1foriinrange(2,n+1):dp[i]=dp[i-1]+dp[i-2]returndp[n]示例print(fibonacci(10))#输出55题目4（5分）：请解释什么是图的深度优先搜索(DFS)，并给出一个DFS的Python实现。pythondefdfs(graph,start,visited=None):ifvisitedisNone:visited=set()visited.add(start)print(start,end='')forneighboringraph[start]:ifneighbornotinvisited:dfs(graph,neighbor,visited)returnvisited示例graph={'A':['B','C'],'B':['A','D','E'],'C':['A','F'],'D':['B'],'E':['B','F'],'F':['C','E']}dfs(graph,'A')二、算法与设计（30分，共6题）题目5（5分）：请解释什么是贪心算法，并给出一个贪心算法的经典问题及其解法。python背包问题（贪心解法）defknapsack(values,weights,capacity):items=sorted(zip(values,weights),key=lambdax:x[0]/x[1],reverse=True)total_value=0remaining_capacity=capacityforvalue,weightinitems:ifweight<=remaining_capacity:total_value+=valueremaining_capacity-=weightelse:fraction=remaining_capacity/weighttotal_value+=valuefractionbreakreturntotal_value示例values=[60,100,120]weights=[10,20,30]capacity=50print(knapsack(values,weights,capacity))#输出240.0题目6（5分）：请解释什么是分治算法，并给出一个分治算法的经典问题及其解法。python快速排序（分治算法）defquicksort(arr):iflen(arr)<=1:returnarrpivot=arr[len(arr)//2]left=[xforxinarrifx<pivot]middle=[xforxinarrifx==pivot]right=[xforxinarrifx>pivot]returnquicksort(left)+middle+quicksort(right)示例print(quicksort([3,6,8,10,1,2,1]))题目7（5分）：请设计一个LRU（最近最少使用）缓存，要求实现get和put操作。pythonclassLRUCache:def__init__(self,capacity):self.capacity=capacityself.cache={}self.order=[]defget(self,key):ifkeyinself.cache:self.order.remove(key)self.order.append(key)returnself.cache[key]return-1defput(self,key,value):ifkeyinself.cache:self.order.remove(key)eliflen(self.cache)>=self.capacity:oldest=self.order.pop(0)delself.cache[oldest]self.cache[key]=valueself.order.append(key)示例lru=LRUCache(2)lru.put(1,1)lru.put(2,2)print(lru.get(1))#返回1lru.put(3,3)#去除键2print(lru.get(2))#返回-1(未找到)题目8（5分）：请设计一个简单的表达式求值器，支持加减乘除。pythondefevaluate_expression(expr):defparse(tokens):values=[]ops=[]i=0whilei<len(tokens):iftokens[i].isdigit():num=0whilei<len(tokens)andtokens[i].isdigit():num=num10+int(tokens[i])i+=1values.append(num)i-=1eliftokens[i]in"+-/":while(opsandops[-1]in"/"and(tokens[i]in"+-"or(tokens[i]in"-"andops[-1]=="")or(tokens[i]in"-/"andops[-1]=="/"))):values.append(apply_op(values.pop(),values.pop(),ops.pop()))ops.append(tokens[i])i+=1whileops:values.append(apply_op(values.pop(),values.pop(),ops.pop()))returnvalues[0]defapply_op(b,a,op):ifop=='+':returna+bifop=='-':returna-bifop=='':returnabifop=='/':returna/btokens=expr.replace('','')returnparse(tokens.split())示例print(evaluate_expression("3+52-8/4"))#输出9.0题目9（5分）：请设计一个简单的Trie（前缀树），支持插入和搜索操作。pythonclassTrieNode:def__init__(self):self.children={}self.is_end=FalseclassTrie:def__init__(self):self.root=TrieNode()definsert(self,word):node=self.rootforcharinword:ifcharnotinnode.children:node.children[char]=TrieNode()node=node.children[char]node.is_end=Truedefsearch(self,word):node=self.rootforcharinword:ifcharnotinnode.children:returnFalsenode=node.children[char]returnnode.is_enddefstarts_with(self,prefix):node=self.rootforcharinprefix:ifcharnotinnode.children:returnFalsenode=node.children[char]returnTrue示例trie=Trie()trie.insert("apple")trie.insert("app")print(trie.search("apple"))#返回Trueprint(trie.search("app"))#返回Trueprint(trie.search("ap"))#返回Falseprint(trie.starts_with("app"))#返回True题目10（5分）：请设计一个简单的线程安全计数器，支持增加和获取当前值操作。pythonfromthreadingimportLockclassThreadSafeCounter:def__init__(self):self.value=0self.lock=Lock()defincrement(self):withself.lock:self.value+=1defget(self):withself.lock:returnself.value示例counter=ThreadSafeCounter()counter.increment()counter.increment()print(counter.get())#输出2三、系统设计（40分，共4题）题目11（10分）：请设计一个简单的URL短链接服务，包括生成短链接和解析短链接的功能。pythonimporthashlibimportrandomclassShortLinkService:def__init__(self):self.base_url="http://short.url/"self.alphabet="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"self.url_map={}def_hash_url(self,long_url):hash_object=hashlib.md5(long_url.encode())returnhash_object.hexdigest()def_generate_short_code(self):code=''.join(random.choice(self.alphabet)for_inrange(6))returncodedefcreate_short_link(self,long_url):hash_code=self._hash_url(long_url)short_code=self._generate_short_code()whileshort_codeinself.url_map:short_code=self._generate_short_code()self.url_map[short_code]=long_urlreturnf"{self.base_url}{short_code}"defget_long_link(self,short_code):returnself.url_map.get(short_code,None)示例service=ShortLinkService()long_url="/very/long/url"short_url=service.create_short_link(long_url)print(short_url)print(service.get_long_link(short_url.split('/')[-1]))#返回原始URL题目12（10分）：请设计一个简单的消息队列系统，支持生产者和消费者模式。pythonfromcollectionsimportdequefromthreadingimportLock,ThreadimporttimeclassMessageQueue:def__init__(self,capacity=100):self.queue=deque()self.capacity=capacityself.lock=Lock()self.not_empty=Noneself.not_full=Nonedefproduce(self,message):withself.lock:whilelen(self.queue)>=self.capacity:self.not_full.wait()self.queue.append(message)self.not_empty.notify()print(f"Produced:{message}")defconsume(self):withself.lock:whilenotself.queue:self.not_empty.wait()message=self.queue.popleft()self.not_full.notify()print(f"Consumed:{message}")returnmessagedefstart(self,num_producers,num_consumers):self.not_empty=threading.Condition(self.lock)self.not_full=threading.Condition(self.lock)producers=[Thread(target=self._produce)for_inrange(num_producers)]consumers=[Thread(target=self._consume)for_inrange(num_consumers)]forpinproducers:p.start()forcinconsumers:c.start()forpinproducers:p.join()forcinconsumers:c.join()def_produce(self):foriinrange(20):time.sleep(random.random())duce(f"Message{i}")def_consume(self):for_inrange(20):time.sleep(random.random())self.consume()示例queue=MessageQueue(10)queue.start(3,2)题目13（10分）：请设计一个简单的分布式缓存系统，支持缓存设置和获取操作。pythonimportrandomimporttimefromthreadingimportLockclassDistributedCache:def__init__(self,nodes):self.nodes=nodesself.cache={}self.lock=Lock()def_get_node(self,key):hash_code=hash(key)%len(self.nodes)returnself.nodes[hash_code]defset(self,key,value,ttl=None):node=self._get_node(key)withself.lock:ifttl:self.cache[key]={'value':value,'expiry':time.time()+ttl}else:self.cache[key]={'value':value,'expiry':None}defget(self,key):node=self._get_node(key)withself.lock:entry=self.cache.get(key)ifentry:ifentry['expiry']isNoneorentry['expiry']>time.time():returnentry['value']else:delself.cache[key]returnNonereturnNone示例nodes=['node1','node2','node3']cache=DistributedCache(nodes)cache.set('key1','value1',ttl=10)print(cache.get('key1'))#输出value1time.sleep(11)print(cache.get('key1'))#输出None题目14（10分）：请设计一个简单的秒杀系统，支持用户下单和库存更新操作。pythonfromthreadingimportLock,TimerimporttimeimportrandomclassSecKillSystem:def__init__(self,total_stock):self.total_stock=total_stockself.stock=total_stockself.lock=Lock()self.order_lock=Lock()self.orders={}self.start_time=time.time()self.end_time=self.start_time+10#10秒秒杀def_check_time(self):iftime.time()>self.end_time:print("秒杀结束")returnTruereturnFalsedefparticipate(self,user_id,quantity):ifself._check_time():returnFalsewithself.lock:ifself.stock<quantity:returnFalseself.stock-=quantityreturnTruedefconfirm_order(self,user_id,quantity):withself.order_lock:ifuser_idnotinself.orders:self.orders[user_id]=0self.orders[user_id]+=quantityprint(f"用户{user_id}订单确认，数量{quantity}")defrun(self):deftick():ifself._check_time():returnTimer(1,tick).start()Timer(1,tick).start()deffinish(self):withself.lock:print(f"秒杀结束，剩余库存{self.stock}")withself.order_lock:foruser_id,quantityinself.orders.items():print(f"用户{user_id}最终订单数量{quantity}")示例sec_kill=SecKillSystem(100)sec_kill.run()users=[1,2,3,4,5]foruserinusers:quantity=random.randint(1,5)ifsec_kill.participate(user,quantity):sec_kill.confirm_order(user,quantity)sec_kill.finish()四、数据库与系统运维（30分，共4题）题目15（10分）：请解释什么是数据库索引，并说明其在查询优化中的作用。请给出一个简单的SQL查询优化示例。sql--原始查询SELECTFROMordersWHEREcustomer_id=123ANDorder_date>'2025-01-01';--优化后的查询--1.在customer_id和order_date上创建复合索引CREATEINDEXidx_customer_dateONorders(customer_id,order_date);--2.优化后的查询利用索引SELECTFROMordersWHEREcustomer_id=123ANDorder_date>'2025-01-01';题目16（10分）：请解释什么是数据库事务，并说明其ACID特性。请给出一个简单的数据库事务示例。sql--示例：银行转账事务BEGINTRANSACTION;--1.从账户A扣除金额UPDATEaccountsSETbalance=balance-100WHEREaccount_id=1;--2.检查账户A余额是否足够IF(SELECTbalanceFROMaccountsWHEREaccount_id=1)>=100BEGIN--3.向账户B添加金额UPDATEaccounts